X-ray and/or metal detectable articles and method of making the same

ABSTRACT

An article and thermoplastic composition including polycarbonate, a polysiloxane-polycarbonate and an x-ray detectable or metal detectable agent having good magnetic permeability and/or electrical conductivity wherein the composition may be used in articles for food preparation. The thermoplastic compositions are useful in forming molds for manufacturing a food product, such as chocolate molds.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/570,421, filed Sep. 30, 2009, which is acontinuation-in-part of U.S. patent application Ser. No. 12/242,076filed Sep. 30, 2008 and claims priority to U.S. Provisional PatentApplication No. 61/153,140 filed Feb. 17, 2009, the contents of whichare hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention is directed to thermoplastic compositions havingimproved metal detectability, and in particular thermoplasticcompositions including polycarbonate, a polysiloxane-polycarbonatepolymer and an X-ray contrast agents or a metal detectable agent,methods of making and of improving x-ray and/or metal detectability inthermoplastics, and articles prepared therefrom.

Polycarbonate molds are commonly used in food production, such aschocolate molds. Such molds are generally made by plastic injectionmold-making which involves high pressure injection of a polycarbonateresin around a metal master. Such polycarbonate molds have a long usefullife and are very strong, and are desirable for both ease of use and formaking high gloss chocolates. Other types of molds such as those made ofsilicone rubber or thermoformed plastic are also used for a limited setof applications.

Metal detectors are commonly used in the manufacturing process to detectmetallic contaminants that typically arise from wear and tear ofmachines resulting from routine use, to ensure that food, such aschocolate, prepared from them are of the highest quality. However, metaldetectors are not capable of detecting any contaminants coming fromplastic components (such as a chocolate mold) in the manufacturingprocess. X-ray detectors can be used to detect plastics; however,polycarbonate and typical compositions, such as for example those usefulfor preparing chocolate molds, are transparent to X-rays. Elementshaving higher atomic numbers than carbon have to be introduced intopolycarbonate, either in the form of additives (e.g., glass, pigments,etc.) or incorporated into the polymer chain, to enable articlesprepared from the polycarbonate to show any level of X-ray contrast.Typically addition of glass or other inorganic fillers leads to loss ofgloss and low transparency as well as reduction in flow and impactproperties of polycarbonate. This is not acceptable in those matriceswhere low temperature ductility in combination with good flow isimportant.

BRIEF SUMMARY OF THE INVENTION

The above-described and other drawbacks are alleviated by, in anembodiment, an article comprising a thermoplastic compositioncomprising: a polysiloxane-polycarbonate; optionally, a polycarbonate;and an X-ray contrast agent comprising X-ray scattering atoms having anatomic number of greater than or equal to 22; wherein an article moldedfrom the thermoplastic composition and having a thickness of 3.2 mm hasa notched Izod impact (NII) strength of greater than or equal to about620 J/m, when measured at a temperature of 0° C. according to ASTMD256-04, or a notched Izod impact strength of greater than or equal toabout 409 J/m, when measured at a temperature of −30° C. according toASTM D256-04, wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has an Equivalent AlThickness of greater than 0.51 mm, when irradiated with 50 kV X-rayradiation, and wherein for melt volume rates of the thermoplasticcomposition determined under a load of 1.2 kg at a temperature of 300°C. according to ASTM D1238-04, a melt volume rate measured at a dwelltime of 18 minutes increases relative to a melt volume rate measured ata dwell time of 6 minutes by less than or equal to 31%.

In another embodiment, a thermoplastic composition comprises: 5 to 100parts by weight of a polysiloxane-polycarbonate; 0 to 95 parts by weightof a polycarbonate; and 0.01 to 10 parts by weight of a contrast agentcomprising rutile titanate having a median particle size of less than orequal to about 5 micrometers (□m), magnetite having a median particlesize of less than about 1 micrometer, or a combination comprising atleast one of the foregoing contrast agents; wherein each of thepolysiloxane-polycarbonate, polycarbonate, and X-ray contrast agent arepresent based on a combined 100 parts by weight ofpolysiloxane-polycarbonate and polycarbonate; wherein an article moldedfrom the thermoplastic composition and having a thickness of 3.2 mm hasa notched Izod impact (NII) strength of greater than or equal to about620 J/m, when measured at a temperature of 0° C. according to ASTMD256-04, or a notched Izod impact strength of greater than or equal toabout 409 J/m, when measured at a temperature of −30° C. according toASTM D256-04, wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has an Equivalent AlThickness of greater than 0.51 mm, when irradiated with 50 kV X-rayradiation, and wherein for melt volume rates of the thermoplasticcomposition determined under a load of 1.2 kg at a temperature of 300°C. according to ASTM D1238-04, a melt volume rate measured at a dwelltime of 18 minutes increases relative to a melt volume rate measured ata dwell time of 6 minutes by less than or equal to 31%.

In another embodiment, a method for increasing the x-ray contrast in anarticle comprises a thermoplastic composition, comprising combining anX-ray contrast agent having a median particle size of less than or equalto 5 micrometers, with a polysiloxane-polycarbonate, and optionally apolycarbonate, wherein the X-ray contrast agent comprises an elementhaving an atomic number of greater than or equal to 22; and forming thearticle from the thermoplastic composition, wherein an article moldedfrom the thermoplastic composition and having a thickness of 3.2 mm hasa notched Izod impact (NII) strength of greater than or equal to about620 J/m, when measured at a temperature of 0° C. according to ASTMD256-04, or a notched Izod impact strength of greater than or equal toabout 409 J/m, when measured at a temperature of −30° C. according toASTM D256-04, wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has an Equivalent AlThickness of greater than 0.51 mm, when irradiated with 50 kV X-rayradiation, and wherein for melt volume rates of the thermoplasticcomposition determined under a load of 1.2 kg at a temperature of 300°C. according to ASTM D1238-04, a melt volume rate measured at a dwelltime of 18 minutes increases relative to a melt volume rate measured ata dwell time of 6 minutes by less than or equal to 31%.

In another embodiment, a mold for manufacturing chocolate comprises athermoplastic composition comprising: 5 to 99 parts by weight of apolysiloxane-polycarbonate, 1 to 95 parts by weight of a polycarbonate,and 0.01 to 10 parts by weight of an X-ray contrast agent comprisingrutile titanate having a median particle size of less than or equal toabout 5 micrometers, magnetite having a median particle size of lessthan or equal to about 0.5 micrometers, or a combination comprising atleast one of the foregoing X-ray contrast agents, wherein each of thepolysiloxane-polycarbonate, polycarbonate, and X-ray contrast agent arepresent based on a combined 100 parts by weight ofpolysiloxane-polycarbonate and polycarbonate, wherein an article moldedfrom the thermoplastic composition and having a thickness of 3.2 mm hasa notched Izod impact (NII) strength of greater than or equal to about620 J/m, when measured at a temperature of 0° C. according to ASTMD256-04, or a notched Izod impact strength of greater than or equal toabout 409 J/m, when measured at a temperature of −30° C. according toASTM D256-04, wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has an Equivalent AlThickness of greater than 0.51 mm, when irradiated with 50 kV X-rayradiation, and wherein for melt volume rates of the thermoplasticcomposition determined under a load of 1.2 kg at a temperature of 300°C. according to ASTM D1238-04, a melt volume rate measured at a dwelltime of 18 minutes increases relative to a melt volume rate measured ata dwell time of 6 minutes by less than or equal to 31%.

Alternatively, the above-described and other drawbacks are alleviatedby, in an embodiment, an article including a thermoplastic compositionincluding: polycarbonate, a polysiloxane-polycarbonate and a metaldetectable agent having good magnetic permeability and/or electricalconductivity; wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has a notched Izod impact(NII) strength of greater than or equal to 300 J/m, when measured at atemperature of 23° C. according to ASTM D256-04, or a notched Izodimpact strength of greater than or equal to 150 J/m, when measured at atemperature of 0° C. according to ASTM D256-04. The thermoplasticcompositions are useful in forming molds for manufacturing a foodproduct, such as chocolate molds.

Accordingly, in one embodiment, the present invention provides athermoplastic composition that includes 65 to 95 parts by weight ofpolycarbonate, 5 to 35 parts by weight of a polysiloxane-polycarbonateand 0.01 to 10 parts by weight of a metal detectable agent; wherein anarticle molded from the thermoplastic composition and having a thicknessof 3.2 mm has a notched Izod impact (NII) strength of greater than orequal to 200 J/m, when measured at a temperature of 23° C. according toASTM D256-04, or a notched Izod impact strength of greater than or equalto 125 J/m, when measured at a temperature of 0° C. according to ASTMD256-04.

In another embodiment, the present invention provides method forincreasing the metal detectability in an article including athermoplastic composition, and including the steps of combining a metaldetectable agent with polycarbonate and a polysiloxane-polycarbonate,wherein the metal detectable agent is selected from a ferrous metal or anon-ferrous metal, and forming the article from the thermoplasticcomposition; wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has a notched Izod impact(NII) strength of greater than or equal to 200 J/m, when measured at atemperature of 23° C. according to ASTM D256-04, or a notched Izodimpact strength of greater than or equal to 125 J/m, when measured at atemperature of 0° C. according to ASTM D256-04.

In yet another embodiment, the present invention provides a mold formanufacturing a food product that includes a thermoplastic compositionhaving 65 to 95 parts by weight of polycarbonate, 5 to 35 parts byweight of a polysiloxane-polycarbonate and 0.01 to 10 parts by weight ofa metal detectable agent; wherein an article molded from thethermoplastic composition and having a thickness of 3.2 mm has a notchedIzod impact (NII) strength of greater than or equal to 200 J/m, whenmeasured at a temperature of 23° C. according to ASTM D256-04, or anotched Izod impact strength of greater than or equal to 125 J/m, whenmeasured at a temperature of 0° C. according to ASTM D256-04.

A description of the figures, which are meant to be exemplary and notlimiting, is provided below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an X-ray image of a chocolate bar taken at (A) 70 kV using afilter, and (B) 50 kV taken without a filter.

FIG. 2 is an X-ray image of a chocolate bar with pellets of an exemplarythermoplastic composition having X-ray contrast, scattered over thesurface of the chocolate bar, taken at (A) 70 kV using a filter, and (B)50 kV taken without a filter.

FIG. 3 shows X-ray images of a chocolate bar and an article (circular inA and B, oblong in C and D) placed on the chocolate bar, in which thearticles are molded from the composition of (A) Example 4, (B) Example5, (C) Example 7, and (D) Example 8.

FIG. 4 shows a plot of ejection pressure versus cycle time todemonstrate mold release properties for articles molded from apolycarbonate control, Example 9, and Comparative Examples 13 and 14.

FIGS. 5 and 6 are graphs showing impact strength and impact retention ofmolded articles made according to the metal-detectable concepts of thepresent invention as compared to prior art compositions and showing 0,3.5 and 5 total wt. % Si.

FIG. 7 is a graph showing fatigue data for metal detectable compositionsof the present invention as compared to prior art compositions, againshowing 0, 3.5 and 5 total wt. % Si.

The above described and other features are exemplified by the followingdetailed description.

DETAILED DESCRIPTION OF THE INVENTION

This disclosure provides a thermoplastic composition that is detectableby an x-ray detector or a metal detector and is prepared frompolycarbonate, a polysiloxane-polycarbonate copolymer and an x-raycontrast agent or a metal detectable agent. Articles made from thethermoplastic composition are also disclosed.

It has been found that certain compounds are useful as metal detectableagents for formulating the metal detectable thermoplastic composition.Specifically useful compounds include ferrous metals and nonferrousmetals, such as magnetite, selected from within an optimal particle sizerange. These compounds are useful in formulating such metal detectablecompositions having the aforementioned properties. Common inorganiccompounds useful as metal detectable agents are selected from ferrousmetals (having both good magnetic permeability and electricalconductivity) and nonferrous metals (which have poor magneticpermeability but good electrical conductivity). The particle size of themetal detectable agent is selected such that select properties (flow,low temperature impact, gloss) of the composition are maintained.

The thermoplastic compositions used in the present invention includeboth a polycarbonate and a polysiloxane-polycarbonate copolymer, alsoreferred to as a polysiloxane-polycarbonate. As used herein, the terms“polycarbonate” and “polycarbonate resin” mean compositions havingrepeating structural carbonate units of the formula (1):

in which at least 60 percent of the total number of R¹ groups arearomatic organic radicals and the balance thereof are aliphatic,alicyclic, or aromatic radicals. In one embodiment, each R¹ is anaromatic organic radical, for example a radical of the formula (2):-A¹-Y¹-A²-  (2)wherein each of A¹ and A² is a monocyclic divalent aryl radical and Y¹is a bridging radical having one or two atoms that separate A¹ from A².In an exemplary embodiment, one atom separates A¹ from A². Illustrativenon-limiting examples of radicals of this type are —O—, —S—, —S(O)—,—S(O)₂—, —C(O)—, methylene, cyclohexyl-methylene,2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene,neopentylidene, cyclohexylidene, cyclopentadecylidene,cyclododecylidene, and adamantylidene. The bridging radical Y¹ may be ahydrocarbon group or a saturated hydrocarbon group such as methylene,cyclohexylidene, or isopropylidene.

Polycarbonates may be produced by the reaction of dihydroxy compoundshaving the formula HO—R¹—OH, which includes dihydroxy compounds offormula (3):HO-A¹-Y¹-A²-OH  (3)wherein Y¹, A¹ and A² are as described above. Also included arebisphenol compounds of general formula (4):

wherein R^(a) and R^(b) each represent a halogen atom or a monovalenthydrocarbon group and may be the same or different; p and q are eachindependently integers of 0 to 4; and X^(a) represents one of the groupsof formula (5):

wherein R^(c) and R^(d) each independently represent a hydrogen atom ora monovalent linear or cyclic hydrocarbon group and R^(e) is a divalenthydrocarbon group.

In an embodiment, a heteroatom-containing cyclic alkylidene groupincludes at least one heteroatom with a valency of 2 or greater, and atleast two carbon atoms. Heteroatoms for use in the heteroatom-containingcyclic alkylidene group include —O—, —S—, and —N(Z)—, where Z is asubstituent group selected from hydrogen, hydroxy, C₁₋₁₂ alkyl, C₁₋₁₂alkoxy, or C₁₋₁₂ acyl. Where present, the cyclic alkylidene group orheteroatom-containing cyclic alkylidene group may have 3 to 20 atoms,and may be a single saturated or unsaturated ring, or fused polycyclicring system wherein the fused rings are saturated, unsaturated, oraromatic.

Other bisphenols containing substituted or unsubstituted cyclohexaneunits can be used, for example bisphenols of formula (6):

wherein each R^(f) is independently hydrogen, C₁₋₁₂ alkyl, or halogen;and each R^(g) is independently hydrogen or C₁₋₁₂ alkyl. Thesubstituents may be aliphatic or aromatic, straight chain, cyclic,bicyclic, branched, saturated, or unsaturated. Suchcyclohexane-containing bisphenols, for example the reaction product oftwo moles of a phenol with one mole of a hydrogenated isophorone, areuseful for making polycarbonate polymers with high glass transitiontemperatures and high heat distortion temperatures. Cyclohexyl bisphenolcontaining polycarbonates, or a combination including at least one ofthe foregoing with other bisphenol polycarbonates, are supplied by BayerCo. under the APEC® trade name.

Other useful dihydroxy compounds having the formula HO—R¹—OH includearomatic dihydroxy compounds of formula (7):

wherein each R^(h) is independently a halogen atom, a C₁₋₁₀ hydrocarbylsuch as a C₁₋₁₀ alkyl group, a halogen substituted C₁₋₁₀ hydrocarbylsuch as a halogen-substituted C₁₋₁₀ alkyl group, and n is 0 to 4. Thehalogen is usually bromine.

Exemplary dihydroxy compounds include the following:4,4′-dihydroxybiphenyl, 1,6-dihydroxynaphthalene,2,6-dihydroxynaphthalene, bis(4-hydroxyphenyl)methane,bis(4-hydroxyphenyl)diphenylmethane,bis(4-hydroxyphenyl)-1-naphthylmethane, 1,2-bis(4-hydroxyphenyl)ethane,1,1-bis(4-hydroxyphenyl)-1-phenylethane,2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane,bis(4-hydroxyphenyl)phenylmethane,2,2-bis(4-hydroxy-3-bromophenyl)propane, 1,1-bis(hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)isobutene,1,1-bis(4-hydroxyphenyl)cyclododecane,trans-2,3-bis(4-hydroxyphenyl)-2-butene,2,2-bis(4-hydroxyphenyl)adamantine, (alpha,alpha′-bis(4-hydroxyphenyl)toluene, bis(4-hydroxyphenyl)acetonitrile,2,2-bis(3-methyl-4-hydroxyphenyl)propane,2,2-bis(3-ethyl-4-hydroxyphenyl)propane,2,2-bis(3-n-propyl-4-hydroxyphenyl)propane,2,2-bis(3-isopropyl-4-hydroxyphenyl)propane,2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane,2,2-bis(3-t-butyl-4-hydroxyphenyl)propane,2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,2,2-bis(3-allyl-4-hydroxyphenyl)propane,2,2-bis(3-methoxy-4-hydroxyphenyl)propane,2,2-bis(4-hydroxyphenyl)hexafluoropropane,1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene,4,4′-dihydroxybenzophenone, 3,3-bis(4-hydroxyphenyl)-2-butanone,1,6-bis(4-hydroxyphenyl)-1,6-hexanedione, ethylene glycolbis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ether,bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide,bis(4-hydroxyphenyl)sulfone, 9,9-bis(4-hydroxyphenyl)fluorine,2,7-dihydroxypyrene,6,6′-dihydroxy-3,3,3′,3′-tetramethylspiro(bis)indane (“spirobiindanebisphenol”), 3,3-bis(4-hydroxyphenyl)phthalide,2,6-dihydroxydibenzo-p-dioxin, 2,6-dihydroxythianthrene,2,7-dihydroxyphenoxathin, 2,7-dihydroxy-9,10-dimethylphenazine,3,6-dihydroxydibenzofuran, 3,6-dihydroxydibenzothiophene, and2,7-dihydroxycarbazole, resorcinol, substituted resorcinol compoundssuch as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl resorcinol,5-butyl resorcinol, 5-t-butyl resorcinol, 5-phenyl resorcinol, 5-cumylresorcinol, 2,4,5,6-tetrafluoro resorcinol, 2,4,5,6-tetrabromoresorcinol, or the like; catechol; hydroquinone; substitutedhydroquinones such as 2-methyl hydroquinone, 2-ethyl hydroquinone,2-propyl hydroquinone, 2-butyl hydroquinone, 2-t-butyl hydroquinone,2-phenyl hydroquinone, 2-cumyl hydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,3,5,6-tetra-t-butyl hydroquinone, 2,3,5,6-tetrafluorohydroquinone, 2,3,5,6-tetrabromo hydroquinone, and the like, as well ascombinations including at least one of the foregoing dihydroxycompounds.

Specific examples of bisphenol compounds that may be represented byformula (3) include 1,1-bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane(hereinafter “bisphenol A” or “BPA”), 2,2-bis(4-hydroxyphenyl)butane,2,2-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)propane,1,1-bis(4-hydroxyphenyl)n-butane,2,2-bis(4-hydroxy-1-methylphenyl)propane,1,1-bis(4-hydroxy-t-butylphenyl)propane,3,3-bis(4-hydroxyphenyl)phthalimidine,2-phenyl-3,3-bis(4-hydroxyphenyl)phthalimidine (PPPBP), and1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (DMBPC). Combinationsincluding at least one of the foregoing dihydroxy compounds may also beused.

In a specific embodiment, the polycarbonate may be a linear homopolymerderived from bisphenol A, in which each of A¹ and A² is p-phenylene andY¹ is isopropylidene. The polycarbonates may have an intrinsicviscosity, as determined in chloroform at 25° C., of 0.3 to 1.5deciliters per gram (dl/g), specifically 0.45 to 1.0 dl/g. Thepolycarbonates may have a weight average molecular weight (Mw) of 10,000to 100,000 g/mol, as measured by gel permeation chromatography (GPC)using a crosslinked styrene-divinyl benzene column, at a sampleconcentration of 1 milligram per milliliter, and as calibrated withpolycarbonate standards.

In an embodiment, the polycarbonate may have a melt volume flow rate(often abbreviated MVR) measures the rate of extrusion of athermoplastics through an orifice at a prescribed temperature and load.Polycarbonates useful for the formation of articles may have an MVR,measured at 300° C. under a load of 1.2 kg according to ASTM D1238-04 orISO 1133, of 0.5 to 80 cubic centimeters per 10 minutes (cc/10 min). Ina specific embodiment, a useful polycarbonate or combination ofpolycarbonates (i.e., a polycarbonate composition) has an MVR measuredat 300° C. under a load of 1.2 kg according to ASTM D1238-04 or ISO1133, of 0.5 to 20 cc/10 min, specifically 0.5 to 18 cc/10 min, and morespecifically 1 to 15 cc/10 min.

“Polycarbonates” and “polycarbonate resins” as used herein furtherinclude homopolycarbonates, copolymers including different R¹ moietiesin the carbonate (referred to herein as “copolycarbonates”), copolymersincluding carbonate units and other types of polymer units, such asester units, polysiloxane units, and combinations including at least oneof homopolycarbonates and copolycarbonates. As used herein,“combination” is inclusive of blends, mixtures, alloys, reactionproducts, and the like. A specific type of copolymer is a polyestercarbonate, also known as a polyester-polycarbonate. Such copolymersfurther contain, in addition to recurring carbonate chain units of theformula (1), repeating units of formula (8):

wherein R² is a divalent group derived from a dihydroxy compound, andmay be, for example, a C₂₋₁₀ alkylene group, a C₆₋₂₀ alicyclic group, aC₆₋₂₀ aromatic group or a polyoxyalkylene group in which the alkylenegroups contain 2 to 6 carbon atoms, specifically 2, 3, or 4 carbonatoms; and T divalent group derived from a dicarboxylic acid, and maybe, for example, a C₂₋₁₀ alkylene group, a C₆₋₂₀ alicyclic group, aC₆₋₂₀ alkyl aromatic group, or a C₆₋₂₀ aromatic group.

In an embodiment, R² is a C₂₋₃₀ alkylene group having a straight chain,branched chain, or cyclic (including polycyclic) structure. In anotherembodiment, R² is derived from an aromatic dihydroxy compound of formula(4) above. In another embodiment, R² is derived from an aromaticdihydroxy compound of formula (7) above.

Examples of aromatic dicarboxylic acids that may be used to prepare thepolyester units include isophthalic or terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid, and combinations including at least one of theforegoing acids. Acids containing fused rings can also be present, suchas in 1,4-, 1,5-, or 2,6-naphthalenedicarboxylic acids. Specificdicarboxylic acids are terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexane dicarboxylic acid, or combinationsthereof. A specific dicarboxylic acid includes a combination ofisophthalic acid and terephthalic acid wherein the weight ratio ofisophthalic acid to terephthalic acid is 91:9 to 2:98. In anotherspecific embodiment, R² is a C₂₋₆ alkylene group and T is p-phenylene,m-phenylene, naphthalene, a divalent cycloaliphatic group, or acombination thereof. This class of polyester includes the poly(alkyleneterephthalates).

The molar ratio of ester units to carbonate units in the copolymers mayvary broadly, for example 1:99 to 99:1, specifically 10:90 to 90:10,more specifically 25:75 to 75:25, depending on the selected propertiesof the final composition.

Processes such as interfacial polymerization and melt polymerization canbe used manufacture polycarbonates. Although the reaction conditions forinterfacial polymerization may vary, an exemplary process generallyinvolves dissolving or dispersing a dihydric phenol reactant in aqueouscaustic soda or potash, adding the resulting mixture to a suitablewater-immiscible solvent medium, and contacting the reactants with acarbonate precursor in the presence of a catalyst such as triethylamineor a phase transfer catalyst, under controlled pH conditions, e.g., 8 to10. The most commonly used water immiscible solvents include methylenechloride, 1,2-dichloroethane, chlorobenzene, toluene, and the like.

Carbonate precursors include, for example, a carbonyl halide such ascarbonyl bromide or carbonyl chloride, or a haloformate such as abishaloformates of a dihydric phenol (e.g., the bischloroformates ofbisphenol A, hydroquinone, or the like) or a glycol (e.g., thebishaloformate of ethylene glycol, neopentyl glycol, polyethyleneglycol, or the like). Combinations including at least one of theforegoing types of carbonate precursors may also be used. In anexemplary embodiment, an interfacial polymerization reaction to formcarbonate linkages uses phosgene as a carbonate precursor, and isreferred to as a phosgenation reaction.

Among the phase transfer catalysts that may be used are catalysts of theformula (R³)₄Q⁺X, wherein each R³ is the same or different, and is aC₁₋₁₀ alkyl group; Q is a nitrogen or phosphorus atom; and X is ahalogen atom or a C₁₋₈ alkoxy group or C₆₋₁₈ aryloxy group. Useful phasetransfer catalysts include, for example, [CH₃(CH₂)₃]₄NX, [CH₃(CH₂)₃]₄PX,[CH₃(CH₂)₅]₄NX, [CH₃(CH₂)₆]₄NX, [CH₃(CH₂)₄]₄NX, CH₃[CH₃(CH₂)₃]₃NX, andCH₃[CH₃(CH₂)₂]₃NX, wherein X is Cl⁻, Br⁻, a C₁₋₈ alkoxy group or a C₆₋₁₈aryloxy group. An effective amount of a phase transfer catalyst may be0.1 to 10 wt % based on the weight of bisphenol in the phosgenationmixture. In another embodiment an effective amount of phase transfercatalyst may be 0.5 to 2 wt % based on the weight of bisphenol in thephosgenation mixture.

All types of polycarbonate end groups are contemplated as being usefulin the polycarbonate composition, provided that such end groups do notsignificantly adversely affect selected properties of the compositions.

Branched polycarbonate blocks may be prepared by adding a branchingagent during polymerization. These branching agents includepolyfunctional organic compounds containing at least three functionalgroups selected from hydroxyl, carboxyl, carboxylic anhydride,haloformyl, and mixtures of the foregoing functional groups. Specificexamples include trimellitic acid, trimellitic anhydride, trimellitictrichloride, tris-p-hydroxy phenyl ethane, isatin-bis-phenol,tris-phenol TC (1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene),tris-phenol PA (4(4(1,1-bis(p-hydroxyphenyl)-ethyl) alpha,alpha-dimethyl benzyl)phenol), 4-chloroformyl phthalic anhydride,trimesic acid, and benzophenone tetracarboxylic acid. The branchingagents may be added at a level of 0.05 to 2.0 wt %. Mixtures includinglinear polycarbonates and branched polycarbonates may be used.

A chain stopper (also referred to as a capping agent) may be includedduring polymerization. The chain stopper limits molecular weight growthrate, and so controls molecular weight in the polycarbonate. Exemplarychain stoppers include certain mono-phenolic compounds, mono-carboxylicacid chlorides, and/or mono-chloroformates. Mono-phenolic chain stoppersare exemplified by monocyclic phenols such as phenol and C₁-C₂₂alkyl-substituted phenols such as p-cumyl-phenol, resorcinolmonobenzoate, and p- and tertiary-butyl phenol; and monoethers ofdiphenols, such as p-methoxyphenol. Alkyl-substituted phenols withbranched chain alkyl substituents having 8 to 9 carbon atom may bespecifically mentioned. Certain mono-phenolic UV absorbers may also beused as a capping agent, for example4-substituted-2-hydroxybenzophenones and their derivatives, arylsalicylates, monoesters of diphenols such as resorcinol monobenzoate,2-(2-hydroxyaryl)-benzotriazoles and their derivatives,2-(2-hydroxyaryl)-1,3,5-triazines and their derivatives, and the like.

Mono-carboxylic acid chlorides may also be used as chain stoppers. Theseinclude monocyclic, mono-carboxylic acid chlorides such as benzoylchloride, C₁-C₂₂ alkyl-substituted benzoyl chloride, toluoyl chloride,halogen-substituted benzoyl chloride, bromobenzoyl chloride, cinnamoylchloride, 4-nadimidobenzoyl chloride, and combinations thereof;polycyclic, mono-carboxylic acid chlorides such as trimellitic anhydridechloride, and naphthoyl chloride; and combinations of monocyclic andpolycyclic mono-carboxylic acid chlorides. Chlorides of aliphaticmonocarboxylic acids with less than or equal to 22 carbon atoms areuseful. Functionalized chlorides of aliphatic monocarboxylic acids, suchas acryloyl chloride and methacryoyl chloride, are also useful. Alsouseful are mono-chloroformates including monocyclic,mono-chloroformates, such as phenyl chloroformate, alkyl-substitutedphenyl chloroformate, p-cumyl phenyl chloroformate, toluenechloroformate, and combinations thereof.

Alternatively, melt processes may be used to make the polycarbonates.Generally, in the melt polymerization process, polycarbonates may beprepared by co-reacting, in a molten state, the dihydroxy reactant(s)and a diaryl carbonate ester, such as diphenyl carbonate, in thepresence of a transesterification catalyst in a BANBURY® mixer, twinscrew extruder, or the like to form a uniform dispersion. Volatilemonohydric phenol is removed from the molten reactants by distillationand the polymer is isolated as a molten residue. A specifically usefulmelt process for making polycarbonates uses a diaryl carbonate esterhaving electron-withdrawing substituents on the aryls. Examples ofspecifically useful diaryl carbonate esters with electron withdrawingsubstituents include bis(4-nitrophenyl)carbonate,bis(2-chlorophenyl)carbonate, bis(4-chlorophenyl)carbonate, bis(methylsalicyl)carbonate, bis(4-methylcarboxylphenyl)carbonate,bis(2-acetylphenyl) carboxylate, bis(4-acetylphenyl)carboxylate, or acombination including at least one of the foregoing. In addition,transesterification catalysts for use may include phase transfercatalysts of formula (R³)₄Q⁺X above, wherein each R³, Q, and X are asdefined above. Examples of transesterification catalysts includetetrabutylammonium hydroxide, methyltributylammonium hydroxide,tetrabutylammonium acetate, tetrabutylphosphonium hydroxide,tetrabutylphosphonium acetate, tetrabutylphosphonium phenolate, or acombination including at least one of the foregoing.

In addition to the polycarbonates described above, combinations of thepolycarbonate with other thermoplastic polymers, for examplecombinations of homopolycarbonates and/or polycarbonate copolymers withpolyesters, may be used. Useful polyesters may include, for example,polyesters having repeating units of formula (8), which includepoly(alkylene dicarboxylates), liquid crystalline polyesters, andpolyester copolymers. The polyesters described herein are generallycompletely miscible with the polycarbonates when blended.

The polyesters may be obtained by interfacial polymerization ormelt-process condensation as described above, by solution phasecondensation, or by transesterification polymerization wherein, forexample, a dialkyl ester such as dimethyl terephthalate may betransesterified with ethylene glycol using acid catalysis, to generatepoly(ethylene terephthalate). It is possible to use a branched polyesterin which a branching agent, for example, a glycol having three or morehydroxyl groups or a trifunctional or multifunctional carboxylic acidhas been incorporated. Furthermore, it is sometime desirable to havevarious concentrations of acid and hydroxyl end groups on the polyester,depending on the ultimate end use of the composition.

The polyester-polycarbonates may also be prepared by interfacialpolymerization. Rather than utilizing the dicarboxylic acid per se, itis possible, and sometimes even preferred, to employ the reactivederivatives of the acid, such as the corresponding acid halides, inparticular the acid dichlorides and the acid dibromides. Thus, forexample instead of using isophthalic acid, terephthalic acid, or acombination comprising at least one of the foregoing, it is possible toemploy isophthaloyl dichloride, terephthaloyl dichloride, and acombination comprising at least one of the foregoing.

The polyesters may be obtained by interfacial polymerization ormelt-process condensation as described above, by solution phasecondensation, or by transesterification polymerization wherein, forexample, a dialkyl ester such as dimethyl terephthalate may betransesterified with ethylene glycol using acid catalysis, to generatepoly(ethylene terephthalate). It is possible to use a branched polyesterin which a branching agent, for example, a glycol having three or morehydroxyl groups or a trifunctional or multifunctional carboxylic acidhas been incorporated. Furthermore, it is sometime desirable to havevarious concentrations of acid and hydroxyl end groups on the polyester,depending on the ultimate end use of the composition.

Useful polyesters may include aromatic polyesters, poly(alkylene esters)including poly(alkylene arylates), and poly(cycloalkylene diesters).Aromatic polyesters may have a polyester structure according to formula(8), wherein D and T are each aromatic groups as described hereinabove.In an embodiment, useful aromatic polyesters may include, for example,poly(isophthalate-terephthalate-resorcinol) esters,poly(isophthalate-terephthalate-bisphenol-A) esters,poly[(isophthalate-terephthalate-resorcinol)ester-co-(isophthalate-terephthalate-bisphenol-A)] ester, or acombination comprising at least one of these. Also contemplated arearomatic polyesters with a minor amount, e.g., about 0.5 to about 10 wt%, based on the total weight of the polyester, of units derived from analiphatic diacid and/or an aliphatic polyol to make copolyesters.Poly(alkylene arylates) may have a polyester structure according toformula (8), wherein T comprises groups derived from aromaticdicarboxylates, cycloaliphatic dicarboxylic acids, or derivativesthereof. Examples of specifically useful T groups include 1,2-, 1,3-,and 1,4-phenylene; 1,4- and 1,5-naphthylenes; cis- ortrans-1,4-cyclohexylene; and the like. Specifically, where T is1,4-phenylene, the poly(alkylene arylate) is a poly(alkyleneterephthalate). In addition, for poly(alkylene arylate), specificallyuseful alkylene groups D include, for example, ethylene, 1,4-butylene,and bis-(alkylene-disubstituted cyclohexane) including cis- and/ortrans-1,4-(cyclohexylene)dimethylene. Examples of poly(alkyleneterephthalates) include poly(ethylene terephthalate) (PET),poly(1,4-butylene terephthalate) (PBT), and poly(propyleneterephthalate) (PPT). Also useful are poly(alkylene naphthoates), suchas poly(ethylene naphthanoate) (PEN), and poly(butylene naphthanoate)(PBN). A useful poly(cycloalkylene diester) ispoly(cyclohexanedimethylene terephthalate) (PCT). Combinationscomprising at least one of the foregoing polyesters may also be used.

Copolymers comprising alkylene terephthalate repeating ester units withother ester groups may also be useful. Useful ester units may includedifferent alkylene terephthalate units, which can be present in thepolymer chain as individual units, or as blocks of poly(alkyleneterephthalates). Specific examples of such copolymers includepoly(cyclohexanedimethylene terephthalate)-co-poly(ethyleneterephthalate), abbreviated as PETG where the polymer comprises greaterthan or equal to 50 mol % of poly(ethylene terephthalate), andabbreviated as PCTG where the polymer comprises greater than 50 mol % ofpoly(1,4-cyclohexanedimethylene terephthalate).

Poly(cycloalkylene diester)s may also include poly(alkylenecyclohexanedicarboxylate)s. Of these, a specific example ispoly(1,4-cyclohexane-dimethanol-1,4-cyclohexanedicarboxylate) (PCCD),having recurring units of formula (9):

wherein, as described using formula (8), R² is a1,4-cyclohexanedimethylene group derived from 1,4-cyclohexanedimethanol,and T is a cyclohexane ring derived from cyclohexanedicarboxylate or achemical equivalent thereof, and may comprise the cis-isomer, thetrans-isomer, or a combination comprising at least one of the foregoingisomers.

The polycarbonate and polyester and/or polyester-polycarbonate may beused in a weight ratio of 1:99 to 99:1, specifically 10:90 to 90:10, andmore specifically 30:70 to 70:30, depending on the function andproperties desired.

The polyester-polycarbonates may have a weight average molecular weight(M_(w)) of 1,500 to 100,000 g/mol, specifically 1,700 to 50,000 g/mol,more specifically 2,000 to 40,000 g/mol, and still more specifically5,000 to 30,000 g/mol. Molecular weight determinations are performedusing gel permeation chromatography (GPC), using a crosslinkedstyrene-divinylbenzene column and calibrated to polycarbonatereferences. Samples are prepared at a concentration of about 1 mg/ml,and are eluted at a flow rate of about 1.0 ml/min.

Where used, it is desirable for a polyester-polycarbonate to have an MVRof about 5 to about 150 cc/10 min., specifically about 7 to about 125cc/10 min, more specifically about 9 to about 110 cc/10 min, and stillmore specifically about 10 to about 100 cc/10 min., measured at 300° C.and a load of 1.2 kilograms according to ASTM D1238-04. Commercialpolyester blends with polycarbonate are marketed under the trade nameXYLEX®, including for example XYLEX® X7300, and commercialpolyester-polycarbonates are marketed under the tradename LEXAN™ SLXpolymers, including for example LEXAN™ SLX-9000, and are available fromSABIC Innovative Plastics (formerly GE Plastics).

In an embodiment, the thermoplastic composition includes polycarbonatein an amount of 0 to 95 parts by weight, specifically 1 to 95 parts byweight, based on a combined 100 parts by weight ofpolysiloxane-polycarbonate and polycarbonate. In a specific embodiment,the thermoplastic composition includes polycarbonate in an amount of 1to 50 parts by weight, specifically 1 to 45 parts by weight, morespecifically 5 to 40 parts by weight, and still more specifically 10 to35 parts by weight, based on a combined 100 parts by weight ofpolysiloxane-polycarbonate and polycarbonate. In another specificembodiment, the thermoplastic composition includes polycarbonate in anamount of 70 to 95 parts by weight, specifically 75 to 95 parts byweight, more specifically 80 to 95 parts by weight, based on a combined100 parts by weight of polysiloxane-polycarbonate and polycarbonate.

In addition to the polycarbonate, the thermoplastic compositions used inthe present invention include a polysiloxane-polycarbonate copolymerthat also includes a polycarbonate with a polysiloxane. The polysiloxane(also referred to herein as “polydiorganosiloxane”) blocks of thecopolymer include repeating siloxane units (also referred to herein as“diorganosiloxane units”) of formula (10):

wherein each occurrence of R is same or different, and is a C₁₋₁₃monovalent organic radical. For example, R may independently be a C₁-C₁₃alkyl group, C₁-C₁₃ alkoxy group, C₂-C₁₃ alkenyl group, C₂-C₁₃alkenyloxy group, C₃-C₆ cycloalkyl group, C₃-C₆ cycloalkoxy group,C₆-C₁₄ aryl group, C₆-C₁₀ aryloxy group, C₇-C₁₃ arylalkyl group, C₇-C₁₃arylalkoxy group, C₇-C₁₃ alkylaryl group, or C₇-C₁₃ alkylaryloxy group.The foregoing groups may be fully or partially halogenated withfluorine, chlorine, bromine, or iodine, or a combination thereof.Combinations of the foregoing R groups may be used in the samecopolymer.

The value of D in formula (10) may vary widely depending on the type andrelative amount of each component in the thermoplastic composition, theselected properties of the composition, and like considerations.Generally, D may have an average value of 2 to 1,000, specifically 2 to500, more specifically 5 to 100, and still more specifically 5 to 50. Ina specific embodiment, D has an average value of 40 to 50. In anexemplary embodiment, D has an average value of 45. In another specificembodiment, D has an average value of 20 to 40. In another exemplaryembodiment, D has an average value of 30.

Where D is of a lower value, e.g., less than 40, it may be beneficial touse a relatively larger amount of the polycarbonate-polysiloxanecopolymer. Conversely, where D is of a higher value, e.g., greater than40, it may be necessary to use a relatively lower amount of thepolycarbonate-polysiloxane copolymer.

A combination of a first and a second (or more)polysiloxane-polycarbonate copolymer may be used, wherein the averagevalue of D of the first copolymer is less than the average value of D ofthe second copolymer.

In one embodiment, the polydiorganosiloxane blocks are provided byrepeating structural units of formula (11):

wherein D is as defined above; each R may independently be the same ordifferent, and is as defined above; and each Ar may independently be thesame or different, and is a substituted or unsubstituted C₆-C₃₀ aryleneradical, wherein the bonds are directly connected to an aromatic moiety.Useful Ar groups in formula (11) may be derived from a C₆-C₃₀dihydroxyarylene compound, for example a dihydroxyarylene compound offormula (3), (4), or (7) above. Combinations including at least one ofthe foregoing dihydroxyarylene compounds may also be used. Specificexamples of dihydroxyarylene compounds are1,1-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxyphenyl) propane, 2,2-bis(4-hydroxyphenyl)butane,2,2-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)propane,1,1-bis(4-hydroxyphenyl)n-butane,2,2-bis(4-hydroxy-1-methylphenyl)propane,1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl sulphide), and1,1-bis(4-hydroxy-t-butylphenyl)propane. Combinations including at leastone of the foregoing dihydroxy compounds may also be used.

Units of formula (11) may be derived from the corresponding dihydroxycompound of formula (12):

wherein R, Ar, and D are as described above. Compounds of formula (12)may be obtained by the reaction of a dihydroxyarylene compound with, forexample, an alpha, omega-bisacetoxypolydiorangonosiloxane under phasetransfer conditions.

In another embodiment, polydiorganosiloxane blocks include units offormula (13):

wherein R and D are as described above, and each occurrence of R⁴ isindependently a divalent C₁-C₃₀ alkylene, and wherein the polymerizedpolysiloxane unit is the reaction residue of its corresponding dihydroxycompound. In a specific embodiment, the polydiorganosiloxane blocks areprovided by repeating structural units of formula (14):

wherein R and D are as defined above. Each R⁵ in formula (14) isindependently a divalent C₂-C₈ aliphatic group. Each M in formula (13)may be the same or different, and may be a halogen, cyano, nitro, C₁-C₈alkylthio, C₁-C₈ alkyl, C₁-C₈ alkoxy, C₂-C₈ alkenyl, C₂-C₈ alkenyloxygroup, C₃-C₈ cycloalkyl, C₃-C₈ cycloalkoxy, C₆-C₁₀ aryl, C₆-C₁₀ aryloxy,C₇-C₁₂ arylalkyl, C₇-C₁₂ arylalkoxy, C₇-C₁₂ alkylaryl, or C₇-C₁₂alkylaryloxy, wherein each n is independently 0, 1, 2, 3, or 4.

In one embodiment, M is bromo or chloro, an alkyl group such as methyl,ethyl, or propyl, an alkoxy group such as methoxy, ethoxy, or propoxy,or an aryl group such as phenyl, chlorophenyl, or tolyl; R⁵ is adimethylene, trimethylene or tetramethylene group; and R is a C₁₋₈alkyl, haloalkyl such as trifluoropropyl, cyanoalkyl, or aryl such asphenyl, chlorophenyl or tolyl. In another embodiment, R is methyl, or amixture of methyl and trifluoropropyl, or a mixture of methyl andphenyl. In still another embodiment, M is methoxy, n is one, R⁵ is adivalent C₁-C₃ aliphatic group, and R is methyl.

Units of formula (14) may be derived from the corresponding dihydroxypolydiorganosiloxane (15):

wherein R, D, M, R⁵, and n are as described above. Such dihydroxypolysiloxanes can be made by effecting a platinum catalyzed additionbetween a siloxane hydride of formula (16):

wherein R and D are as previously defined, and an aliphaticallyunsaturated monohydric phenol. Useful aliphatically unsaturatedmonohydric phenols included, for example, eugenol, 2-allylphenol,4-allyl-2-methylphenol, 4-allyl-2-phenylphenol, 4-allyl-2-bromophenol,4-allyl-2-t-butoxyphenol, 4-phenyl-2-phenylphenol,2-methyl-4-propylphenol, 2-allyl-4,6-dimethylphenol,2-allyl-4-bromo-6-methylphenol, 2-allyl-6-methoxy-4-methylphenol and2-allyl-4,6-dimethylphenol. Mixtures including at least one of theforegoing may also be used.

The polysiloxane-polycarbonate includes 50 to 99.9 wt % of carbonateunits and 0.1 to 50 wt % siloxane units, specifically 0.1 to 25 wt %siloxane units, based on the total weight of thepolysiloxane-polycarbonate. In a specific embodiment, thepolysiloxane-polycarbonate copolymer includes 90 to 99 wt %, morespecifically 92 to 98 wt %, still more specifically 93 to 97 wt %, andstill more specifically 93 to 96 wt % of carbonate units and 1 to 10 wt%, specifically 2 to 8 wt %, more specifically 3 to 7 wt %, and stillmore specifically 4 to 7 wt % siloxane units. In an exemplary embodimentthe polysiloxane-polycarbonate includes about 6 wt % siloxane units. Inanother specific embodiment, the polysiloxane-polycarbonate copolymerincludes 75 to 90 wt %, more specifically 75 to 85 wt %, still morespecifically 77 to 83 wt %, and still more specifically 78 to 82 wt % ofcarbonate units and 10 to 25 wt %, specifically 15 to 25 wt %, morespecifically 17 to 23 wt %, and still more specifically 18 to 22 wt %siloxane units. In another exemplary embodiment thepolysiloxane-polycarbonate includes about 20 wt % siloxane units. Allreferences to weight percent compositions in thepolysiloxane-polycarbonate are based on the total weight of thepolysiloxane-polycarbonate.

In an embodiment, the polysiloxane-polycarbonate includes polysiloxaneunits, and carbonate units derived from bisphenol A, e.g., the dihydroxycompound of formula (3) in which each of A¹ and A² is p-phenylene and Y¹is isopropylidene. Polysiloxane-polycarbonates may have a weight averagemolecular weight of 2,000 to 100,000 g/mol, specifically 5,000 to 50,000g/mol as measured by gel permeation chromatography using a crosslinkedstyrene-divinyl benzene column, at a sample concentration of 1 milligramper milliliter, and as calibrated with polycarbonate standards.

The polysiloxane-polycarbonate can have a melt volume flow rate,measured at 300° C. under a load of 1.2 kg, of 1 to 50 cubic centimetersper 10 minutes (cc/10 min), specifically 2 to 30 cc/10 min. Mixtures ofpolysiloxane-polycarbonates of different flow properties may be used toachieve the overall selected flow property. In an embodiment, exemplarypolysiloxane-polycarbonates are marketed under the trade name LEXAN™ EXLpolycarbonates, available from SABIC Innovative Plastics (formerly GEPlastics).

In an embodiment, the thermoplastic composition includespolysiloxane-polycarbonate in an amount of 5 to 100 parts by weight,specifically 5 to 99 parts by weight, based on combined 100 parts byweight of polysiloxane-polycarbonate and any added polycarbonate. In aspecific embodiment, the thermoplastic composition includespolysiloxane-polycarbonate in an amount of 50 to 99 parts by weight,specifically 55 to 99 parts by weight, more specifically 60 to 95 partsby weight, and still more specifically 65 to 90 parts by weight, basedon combined 100 parts by weight of polysiloxane-polycarbonate and anyadded polycarbonate. In another specific embodiment, the thermoplasticcomposition includes polysiloxane-polycarbonate in an amount of 5 to 30parts by weight, specifically 5 to 25 parts by weight, and morespecifically 5 to 20 parts by weight, based on a combined 100 parts byweight of polysiloxane-polycarbonate and any added polycarbonate.

In select embodiments, the thermoplastic composition also includes anX-ray contrast agent. The X-ray contrast agent can be an inorganiccompound comprising atoms with an atomic number sufficient to scatterincident X-ray radiation, also referred to herein as X-ray scatteringatoms. In an embodiment, the X-ray contrast agent comprises X-rayscattering atoms having an atomic number of greater than or equal to 22,specifically greater than or equal to 24, more specifically greater thanor equal to 26, and still more specifically greater than or equal to 28.Also in an embodiment, the X-ray contrast agent includes the X-rayscattering atoms in an amount greater than or equal to about 1 percentby weight, more specifically greater than or equal to about 5 percent byweight, and still more specifically greater than or equal to about 10percent by weight, based on the total weight of the X-ray contrastagent.

The X-ray contrast agent is, in one embodiment, in the form ofparticles, and may, depending upon the type used, be a filler, pigment,or other such class of inorganic material having suitable properties asdefined herein. The particles as disclosed herein can be used in anysuitable morphological form, including but not limited tomicroparticles, nanoparticles, and particles having various shapesincluding spheres, rods, faceted crystalline shapes, irregular shapes,and the like. The size of the particles of the X-ray contrast agent, asmeasured by the longest dimension and also referred to as both particlesize and particle size, can be described more generally using the medianof the distribution of the particle sizes, also referred to as themedian particle size. Particle sizes can be determined using variousmethods, typically light scattering methods including static lightscattering (SLS) and dynamic light scattering (DLS), also referred togenerally as laser light scattering techniques. Particles of X-raycontrast agent as disclosed herein have a median particle size (D₅₀), ofless than or equal to about 5 micrometers, specifically less than orequal to 2 micrometers, more specifically less than or equal to 1.5micrometers, and still more specifically less than or equal to about 1micrometer. In a specific embodiment, useful X-ray contrast agents havea median particle size about 0.1 to about 0.5 micrometers, specificallyabout 0.2 to about 0.5 micrometers. In another specific embodiment,useful X-ray contrast agents have a median particle size about 0.5 toabout 1 micrometers, specifically about 0.5 to about 0.9 micrometers.The maximum particle size range (D₉₀, where 90% of the particles aresmaller) for X-ray contrast agents varies with the median particle size,and can in general be about 0.5 to about 30 micrometers, specificallyabout 1 to about 25 micrometers, wherein particles having the maximumparticle size constitute less than 5 wt %, specifically less than 3 wt%, of the total weight of particles of X-ray contrast agent. Thedistribution of median particle sizes of an X-ray contrast agent can beunimodal, bimodal, or multimodal.

X-ray contrast agents can be used in varying stages of compositionalpurity, provided any impurities present in the thermoplastic compositiondo not significantly adversely affect the desired properties of thethermoplastic composition. Where desired, X-ray contrast agents can haveminor amounts of impurities of less than or equal to about 0.1% byweight, more specifically less than or equal to about 0.01% by weight,and still more specifically less than or equal to about 0.001% byweight, based on the total weight of the X-ray contrast agent. In oneembodiment, the X-ray contrast agent can contain minor amounts ofimpurities present as the oxide, hydroxide, carboxylate, carbonate,subcarbonates, phosphate, sulfate, sulfonate, silicate, aluminate, orother salt of metals and/or nonmetals such as lithium, sodium,potassium, magnesium, calcium, barium, silicon, iron, zinc, nickel,copper, boron, aluminum, combinations of these, and the like, in minoramounts so that the desired properties of the thermoplastic compositionare not significantly adversely affected. In another embodiment, theX-ray contrast agent may be treated or purified to remove or reduce thepresence of such impurities, where such impurities are initially present(prior to treating or purification) in the X-ray contrast agent inamounts sufficient to significantly adversely affect the desirableproperties of the composition. The X-ray contrast agents disclosedherein do not require separation or purification of phases to provide asuitable material.

The X-ray contrast agents as used can be untreated, or used as treated,coated, and/or dispersed forms. Any suitable surface coating agent,treatment, or dispersant can be used that is suitable to adjust asdesired the dispersing properties, adhesion properties, or other suchproperties of the X-ray contrast agent particles used herein. Inaddition, it is contemplated that the X-ray contrast agent can be in asingle structured particle, or as a core-shell structured particle, withthe core and shell layers having different phases or compositions. Anysuch structure is contemplated, provided the inclusion of the structuredparticle does not have any significantly adverse effects on theproperties of the thermoplastic composition.

X ray contrast agents as disclosed hereinabove include inorganic, havesufficient X-ray contrast, and do not significantly adversely affect theproperties of a thermoplastic composition prepared therewith. Usefulpigments include, for example, inorganic pigments. Exemplary inorganicpigments include metal oxide hydroxides and metal oxides such as zincoxide, titanium dioxides, iron oxides, chromium oxides, cerium oxide,colored alumina oxide particles, or the like. Inorganic pigments caninclude carbonates, and titanates based on rutile, spinels, priderite,and pseudobrookite pigment structures. As used herein “rutile” is amineral composed primarily of titanium dioxide (TiO₂) and is the mostcommon natural form of TiO₂, along with its two less abundant polymorphsanatase (having a tetragonal, pseudo-octahedral morphology), andbrookite, an orthorhombic mineral. Rutile is a desirable polymorph ofTiO₂ because it has the lowest molecular volume of the three polymorphsof TiO₂ (i.e., rutile, brookite, anatase), hence the highest density.Rutile has among the highest refractive indices of any known mineral.Also as used herein, “spinels” generally are any of a class of mineralsof general formulation XY₂O₄ (where X and Y are each metal cations)which crystallize in the cubic (isometric) crystal system, with theoxide anions arranged in a cubic close-packed lattice and the cations Xand Y occupying some or all of the octahedral and tetrahedral sites inthe lattice, where X and Y can be divalent, trivalent, or quadrivalentcations. Typical X and Y metal cations may include, but are not limitedto, magnesium, zinc, iron, manganese, aluminum, chromium, titanium, andsilicon. The anion in a spinel is typically oxide. Spinels may be normalspinels, in which X cations occupy the tetrahedral sites of the oxidelattice, and Y cations occupy the octahedral sites; or inverse spinelsin which half the Y cations occupy the tetrahedral sites, and both X andY cations occupy the octahedral sites. Inverse spinels can thus havetwice as many filled octahedra as tetrahedra.

Inorganic pigments can include carbonates such as calcium and cobaltcarbonate, titanates based on rutile such as chromium antimony titanateand nickel antimony titanate, spinels such as cobalt and iron titanates,priderite, and pseudobrookite pigment structures. Examples of metal ionsthat may be contained within the rutile lattice include tungsten,cobalt, lithium, cerium, manganese, niobium, barium, tin, and zinc, butthey are not limited to these metal ions. Other exemplary pigmentsinclude: chromites such as copper chromite black and cobalt chromitegreen; ferrites such as the pure ferrite spinels that contain magnesiumand zinc, mixed chromite/ferrite spinels, and mixed chromium ironpigments identified as Pigment Green 17 or Pigment Brown 29; sulfidesand sulfates such as cadmium sulfides and sulfoselenides, ceriumsulfides, zinc sulfide, barium sulfate, and strontium sulfate;chromates; silicates such as ultramarine and zirconium silicate andzircon praseodymium yellow pigments; cyanide complexes such as theFe(II)-Fe(III) cyano complexes (e.g., “Prussian blue”); calcium,lanthanum, and tantalum oxide-nitrides and titanium nitride; manganeseand cobalt phosphates; titania-rare earth mixed oxide pigments;luminescent pigments such as sulfides and sulfoselenides, alkaline-earthsulfides and sulfoselenides, oxysulfides, borates, aluminates, gallates,silicates, germinates, halophosphates and phosphates, oxides, arsenates,and vanadates including yttrium vanadates, niobates and tantalates,sulfates, tungstates and molybdates.

Other inorganic compounds that may be used as X-ray contrast agentsinclude alkali-metal halides, alkaline-earth halides, includinganti-stokes shift pigments, and oxyhalides; quantum effect pigments suchas nanoscale silicon with a particle size less than 5 nanometers;semi-conducting luminescent nanoparticles such as Cd₃P₂, and PbS; andstorage phosphors such as CaS:Eu,Sm. Phosphorescent materials(“phosphors”) may also be used. Such phosphors include ZnS:Cu andSrS:Bi. Phosphors that can be used include those based on MAl₂O₄ whereinM is a metal such as calcium, strontium, barium, or a combinationcomprising at least one of the foregoing metals. The matrix can be dopedwith europium and dysprosium.

Other pigments and dyes may be used as X-ray contrast agents, includingazo lakes (calcium lakes), lanthanide chelates, metal dithiol complexes,phthalocyanines, metalloporphyrin dyes, and1,1′-diethyl-2,2′-carbocyanine iodide. Other colorants that can be usedinclude mica, iron mica, metal oxide mica, antimony trioxide, angularmetameric pigment, cholesteric liquid crystal, metal oxide coated glass,metal flake, or a combination comprising at least one of the foregoingmaterials. In one embodiment, the pigment or color additive is a metalflake having a largest diameter of 17.5 to 650 micrometers. The metalflake can comprise aluminum, bronze, brass, chromium, copper, gold, analloy comprising a least one of the foregoing materials, or acombination comprising at least one of the foregoing materials.Colorants also include materials with magnetic properties e.g., magneticpigments such as chromium dioxide, iron oxides, and cobalt-containingiron oxides. A combination comprising one or more of any of theforegoing different types of additives can be used.

Specific inorganic compounds that are useful as X-ray contrast agentsinclude magnetite and rutile titanate. In one embodiment, the X-raycontrast agent can comprise magnetite, also referred to ferrous-ferricoxide. Magnetite is a ferrimagnetic mineral of chemical formula Fe₂O₄,which can also be written as FeO.Fe₂O₃, comprising one molar equivalentof wüstite (FeO, an iron (II) compound) and one molar equivalent ofhematite (Fe₂O₃, an iron (III) compound). Magnetite may be obtained as amineral, or as a synthetic product prepared by, for example, an aqueoussolution method. In addition to comprising Fe(II) and Fe(III) oxides,magnetites may further include small amounts i.e., less than about 5% byweight in total, of other elements such as for example, phosphorus,silicon, and/or aluminum, where inclusion of one or more of these mayinfluence the particle shape for synthetic magnetites. Particles ofmagnetite may thus be hexahedral, octahedral, twinned, or spherical instructure. Magnetite has an inverse spinel structure. In a specificembodiment, where magnetite is used, the median particle size of themagnetite is less than about 1 micrometer. In a more specificembodiment, the median particle size of magnetite is 0.01 to about 0.5micrometers, specifically about 0.1 to about 0.5 micrometers, and stillmore specifically about 0.2 to about 0.5 micrometers.

In another embodiment, the X-ray contrast agent can comprise a rutiletitanate. Rutile titanates, also referred to as rutile titanatepigments, are pigments that include a rutile (titanium dioxide, TiO₂)crystal structure and at least two metal oxides. Typically, rutiletitanate pigments obtain color by incorporating a color-producingtransition metal ion into the rutile crystal structure of the hostoxide, e.g., titanium dioxide (rutile). Additionally, the rutiletitanates can include metals, such as antimony, tungsten, or niobium.Rutile titanates are chemically neutral, which is desirable to minimizedecomposition where such a pigment is to be included in apolycarbonate-based matrix. Exemplary rutile titanates include PigmentYellow 53 pigment (nickel antimony rutile titanate pigment), PigmentYellow 163 (chromium tungsten rutile titanate orange), and Pigment Brown24 (chromium antimony rutile titanate yellow). Combinations comprisingat least one of the foregoing rutile titanates may be used.

Rutile titanates may be manufactured by any suitable means known in theart. For example, rutile titanates may be prepared by a calcinationprocess, which firstly involves intimately mixing transition metalcompounds (including nickel compounds such as nickel oxide and nickelcarbonate, tantalum compounds, antimony oxide, chromium oxides,manganese oxides, iron oxides, cobalt oxides, mixtures thereof, or thelike) with a titanium compound and any other compound (compounds ofantimony, tungsten, or other additive compounds) together in either awet or dry state in appropriate proportions to form a mixed metal oxide.The titanium compound used can be, for example, titanium dioxide,titanium oxide hydrate, titanium oxide hydroxide, titanyl sulfate,synthetic anatase, ultra-fine rutile or a rutile pigment. As naturalrutile may contain up to 10% by weight of iron and significant amountsof niobium and tantalum, conventional rutile titanate manufacturingprocesses may use synthetic titanium dioxide, prepared by a chloride orsulfate process. Additionally, a chemical compound including a metalcation such as W⁶⁺, Mo⁶⁺, Nb⁵⁺, or Ta⁵⁺, or mixtures thereof can becombined with the rutile ore and the transition metal oxide. The mixedmetal oxide so formed is secondly calcined at high temperature in a kilnor furnace. For example, nickel titanate yellow may be made by mixing anactive grade of nickel carbonate with a finely powdered active grade ofantimony oxide and an active grade of titanium dioxide, and calcining atup to about 1,000° C. until the mixture is fully reacted, to form anickel-antimony titanate.

The thermoplastic composition may also include mixtures of X-raycontrast agents. Thus in addition to magnetite, rutile titanate, or acombination of magnetite and rutile titanate, the thermoplasticcomposition may further include any of the inorganic compounds listedhereinabove provided that any further pigment or filler included doesnot significantly adversely affect the desired properties of thecomposition.

In one embodiment, the thermoplastic composition includes X-ray contrastagent in an amount of about 0.01 to about 10 parts by weight,specifically about 0.05 to about 10 parts by weight, more specificallyabout 0.1 to about 10 parts by weight, still more specifically about 0.1to about 8 parts by weight, and still yet more specifically about 0.1 toabout 6 parts by weight, based on a combined 100 parts by weight ofpolysiloxane-polycarbonate and any added polycarbonate.

In an alternative embodiment to using an x-ray contrast agent, thethermoplastic composition includes a metal detectable agent in lieu ofthe x-ray contrast agent (or, in some embodiments both may be used toensure a composition that may be used with x-ray detectors or metaldetectors). The metal detectable agent can be any ferrous or nonferrousmetal having good magnetic permeability and/or good electricalconductivity. Most standard metal detectors are capable of detectingmaterials that are magnetic, such as those containing iron, such asmagnetite. However, other metal detectors are capable of detecting ametal based on the electrical conductivity of the material, even if thematerial is not magnetic, such as copper or aluminum. The concepts ofthe present invention apply to with regard to any metal detectable agentthat may be formed into particles and that are subsequently capable ofbeing detected using a metal detector, ferrous or nonferrous.

In addition, it has been discovered that for compositions having bothpolycarbonate and a polycarbonate-polysiloxane copolymer, the additionof the metal detectable agent surprisingly helps to retain impactstrength even when less siloxane is included in the final composition.In general, the greater the amount of siloxane in the final composition,the better the impact properties. However, in the compositions of thepresent invention, it has been discovered that better impact properties,such as notched izod impact, can be obtained with compositions havinglower amounts of siloxane and a small amount of metal detectable agent.

The metal detectable agent is in the form of particles, and may,depending upon the type used, be a filler, pigment, or other such classof inorganic material having suitable properties as defined herein. Theparticles as disclosed herein can be used in any suitable morphologicalform, including but not limited to microparticles, nanoparticles, andparticles having various shapes including spheres, rods, facetedcrystalline shapes, irregular shapes, and the like. The size of theparticles of the metal detectable agent, as measured by the longestdimension and also referred to as both particle size and particle size,can be described more generally using the median of the distribution ofthe particle sizes, also referred to as the median particle size.

Particle sizes can be determined using various methods, typically lightscattering methods including static light scattering (SLS) and dynamiclight scattering (DLS), also referred to generally as laser lightscattering techniques. In one embodiment, particles of metal detectableagent as disclosed herein have a median particle size (D₅₀), of greaterthan or equal to 5 micrometers, specifically greater than or equal to 8micrometers, and more specifically greater than or equal to 10micrometers. In an alternative embodiment, the particles of metaldetectable have a median particle size of less than or equal to 50micrometers, specifically less than or equal to 20 micrometers. In aspecific embodiment, useful metal detectable agents have a medianparticle size 5 to 25 micrometers, specifically 5 to 10 micrometers. Themaximum particle size range (D₉₀, where 90% of the particles aresmaller) for Metal detectable agents varies with the median particlesize, and can in general be 5 to 50 micrometers, specifically 5 to 25micrometers, wherein particles having the maximum particle sizeconstitute less than 5 wt %, specifically less than 3 wt %, of the totalweight of particles of Metal detectable agent. The distribution ofmedian particle sizes of a metal detectable agent can be unimodal,bimodal, or multimodal.

In an alternative embodiment, particles of metal detectable agent asdisclosed herein have a median particle size (D₅₀), of less than orequal to 5 micrometers, specifically less than or equal to 2micrometers, more specifically less than or equal to 1.5 micrometers,and still more specifically less than or equal to 1 micrometer. In aspecific embodiment, useful metal detectable agents have a medianparticle size from 0.1 to 0.5 micrometers, specifically 0.2 to 0.5micrometers. In another specific embodiment, useful metal detectableagents have a median particle size 0.5 to 1 micrometer, specifically 0.5to 0.9 micrometers.

Metal detectable agents can be used in varying stages of compositionalpurity, provided any impurities present in the thermoplastic compositiondo not significantly adversely affect the selected properties of thethermoplastic composition. In alternative embodiments, metal detectableagents can have minor amounts of impurities of less than or equal to0.1% by weight, more specifically less than or equal to 0.01% by weight,and still more specifically less than or equal to 0.001% by weight,based on the total weight of the metal detectable agent. In oneembodiment, the Metal detectable agent can contain minor amounts ofimpurities present as the oxide, hydroxide, carboxylate, carbonate,subcarbonates, phosphate, sulfate, sulfonate, silicate, aluminate, orother salt of metals and/or nonmetals such as lithium, sodium,potassium, magnesium, calcium, barium, silicon, iron, zinc, nickel,copper, boron, aluminum, combinations of these, and the like, in minoramounts so that the selected properties of the thermoplastic compositionare not significantly adversely affected. In another embodiment, themetal detectable agent may be treated or purified to remove or reducethe presence of such impurities, where such impurities are initiallypresent (prior to treating or purification) in the metal detectableagent in amounts sufficient to significantly adversely affect theselected properties of the composition. The metal detectable agentsdisclosed herein do not require separation or purification of phases toprovide a suitable material.

The metal detectable agents as used can be untreated, or used astreated, coated, and/or dispersed forms. Any suitable surface coatingagent, treatment, or dispersant can be used that is suitable to adjustas desired the dispersing properties, adhesion properties, or other suchproperties of the metal detectable agent particles used herein. Inaddition, it is contemplated that the metal detectable agent can be in asingle structured particle, or as a core-shell structured particle, withthe core and shell layers having different phases or compositions. Anysuch structure is contemplated, provided the inclusion of the structuredparticle does not have any significantly adverse effects on theproperties of the thermoplastic composition.

Specific compounds that are useful as metal detectable agents includemagnetite. In one embodiment, the metal detectable agent can includemagnetite, as previously discussed. In one embodiment where magnetite isused, the median particle size of the magnetite is greater than 1micrometers. In a more specific embodiment, the median particle size ofmagnetite is 5 to 25 micrometers, specifically 5 to 15 micrometers, andstill more specifically 5 to 10 micrometers. In another embodiment wheremagnetite is used, the median particle size of the magnetite is lessthan about 1 micrometer. In a more specific embodiment, the medianparticle size of magnetite is 0.01 to about 0.5 micrometers,specifically about 0.1 to about 0.5 micrometers, and still morespecifically about 0.2 to about 0.5 micrometers.

The thermoplastic composition may also include mixtures of metaldetectable agents. Thus in addition to magnetite, the thermoplasticcomposition may further include any additional metal detectable agentthat does not significantly adversely affect the selected properties ofthe composition.

In one embodiment, the thermoplastic composition includes a metaldetectable agent in an amount of 0.01 to 10 parts by weight,specifically 0.05 to 10 parts by weight, more specifically 0.1 to 10parts by weight, still more specifically 0.1 to 8 parts by weight, andstill yet more specifically 0.1 to 6 parts by weight, based on acombined 100 parts by weight of polysiloxane-polycarbonate and thepolycarbonate.

Also in another embodiment, the thermoplastic composition has a siloxanecontent of 0.1 to 6 wt %, specifically 0.5 to 6 wt %, more specifically1 to 6 wt %, still more specifically 1 to 5 wt % siloxane units, andstill more specifically 1 to 4 wt % siloxane units, based on the totalweight of the thermoplastic composition.

The thermoplastic composition thus includes polycarbonate,polysiloxane-polycarbonate polymer, and either an x-ray contrast agentor a metal detectable agent or both. In one embodiment, polycarbonatesspecifically useful in the thermoplastic polymer includehomopolycarbonates, copolycarbonates, polyester-polycarbonates, blendsthereof with polyesters, and combinations including at least one of theforegoing polycarbonate-type resins or blends. In a specific embodiment,a thermoplastic composition consists essentially of apolysiloxane-polycarbonate polymer, X-ray contrast agent, and anyadditional polycarbonate; additives and/or fillers may be included butare not essential to the composition. In another specific embodiment,the thermoplastic composition consists of polysiloxane-polycarbonatepolymer and X-ray contrast agent. In another specific embodiment, thethermoplastic composition consists of polysiloxane-polycarbonatepolymer, X-ray contrast agent, and an additional polycarbonate. Inanother specific embodiment, a thermoplastic composition consistsessentially of polycarbonate, a polysiloxane-polycarbonate polymer, ametal detectable agent, and any additives and/or fillers that are notessential to the composition. In another specific embodiment, thethermoplastic composition consists of polysiloxane-polycarbonate polymerand metal detectable agent. In another specific embodiment, thethermoplastic composition consists of polysiloxane-polycarbonatepolymer, metal detectable agent, and an additional polycarbonate.

In addition to the polycarbonate, the polysiloxane-polycarbonatecopolymer and x-ray contrast agent or metal detectable agent, thethermoplastic composition can further include various other additivesordinarily incorporated with thermoplastic compositions of this type,where the additives are selected so as not to significantly adverselyaffect the selected properties of the thermoplastic composition.Mixtures of additives may be used. Such additives may be mixed at asuitable time during the mixing of the components for forming thethermoplastic composition.

Useful additives contemplated herein include, but are not limited to,impact modifiers, fillers, colorants including dyes and pigments,antioxidants, heat stabilizers, light and/or UV light stabilizers,plasticizers, lubricants, mold release agents, flame retardants,antistatic agents, anti-drip agents, radiation (gamma) stabilizers, andthe like, or a combination including at least one of the foregoingadditives. While it is contemplated that other resins and or additivesmay be used in the thermoplastic compositions described herein, suchadditives while useful in some exemplary embodiments are not essential.

Surprisingly, it has been found that a thermoplastic compositioncomprising a polysiloxane-polycarbonate and magnetite or rutile titanateas the X-ray contrast agent in amounts of less than 10 wt % of thethermoplastic composition has, in addition to sufficient X-ray contrast,desirably improved thermal and chemical stability. Thermal and chemicalstability for the polycarbonate groups of the thermoplastic compositionare seen in a minimal or low increase (shift) in melt volume flow rate(MVR) of less than or equal to 31% for MVR values obtained for identicalsamples of the thermoplastic composition at a normal dwell of 6 minutesand at a more punishing dwell of 18 minutes, using MVR measurementconditions of about 300° C. and 1.2 kg of force according to ASTMD1238-04. Any degradation of the polycarbonate-based composition wasthus minimal relative to that observed for non-magnetite or rutiletitanate X-ray contrast agents. Mechanical properties of thethermoplastic composition are also retained when magnetite having asmall median particle size (e.g., less than or equal to about 1.0micrometers) or rutile titanates are used as X-ray contrast agents, inparticular where notched Izod impact (NII) values of greater than orequal to about 409 J/m at −30° C., greater than about 559 J/m at −20°C., and/or greater than or equal to about 620 J/m at 0° C., with 100%retention of ductility at these temperatures (based on 100% of a testset of at least 5 molded samples exhibiting a ductile fracture mode,carried out according to ASTM D256-04). The thermoplastic compositionadditionally exhibits improved ductility at low temperatures (as low as−30° C.) compared to comparable thermoplastic compositions preparedidentically but using X-ray contrast agents (e.g., barium salts, bismuthsalts, spinel pigments, and the like) other than magnetite or rutiletitanate particles.

MVR shift was determined from MVR measurements in units of cc/10 min.made at 300° C. under a load of 1.2 kg, and at dwell times of 6 and 18minutes according to ASTM D1238-04. MVR shift (i.e., increase in MVR) iscalculated according to the following equation:MVR Shift (%)={[(MVR@18 min)−(MVR@6 min)]/[MVR@6 min]}×100,where MVR @ 18 min. represents the MVR determined at a dwell time of 18minutes, and MVR @ 6 min. represents the MVR determined at a dwell timeof 6 minutes. Thus, in an embodiment, for melt volume rates of thethermoplastic composition determined under a load of 1.2 kg at atemperature of 300° C. according to ASTM D1238-04, a melt volume ratemeasured at a dwell time of 18 minutes increases relative to a meltvolume rate measured at a dwell time of 6 minutes by less than or equalto 31%, specifically by less than or equal to about 20%, and morespecifically by less than or equal to 16%.

Surprisingly, it has also been found that a thermoplastic compositionincluding polycarbonate, a polysiloxane-polycarbonate and magnetite asthe metal detectable agent in amounts of less than 10 wt % of thethermoplastic composition can be used to create a metal detectablepolycarbonate-polysiloxane formulation. The particle size of themagnetite is so chosen that key properties (flow, low temperatureimpact, gloss) of the composition are capable of being maintained.Mechanical properties of the thermoplastic composition are also retainedwhen magnetite having a selected median particle size is used as themetal detectable agent, in particular, to form articles that, whenmolded from the thermoplastic composition and having a thickness of 3.2mm, has a notched Izod impact (NII) strength of greater than or equal to300 J/m, when measured at a temperature of 23° C. according to ASTMD256-04, or a notched Izod impact strength of greater than or equal to150 J/m, when measured at a temperature of 0° C. according to ASTMD256-04 (based on 100% of a test set of at least 5 molded samplesexhibiting a ductile fracture mode, carried out according to ASTMD256-04).

In embodiments using an x-ray contrast agent, an article molded from thethermoplastic composition and having a thickness of 3.2 mm has a notchedIzod impact (NII) strength of greater than or equal to about 621 J/m,specifically greater than or equal to about 689 J/m, more specificallygreater than or equal to about 690 J/m, and still more specificallygreater than or equal to about 694 J/m, when measured at a temperatureof 23° C., according to ASTM D256-04. Also in this embodiment, for atest set of at least 5 molded articles of 3.2 mm thickness and moldedfrom the thermoplastic composition, 100% of the articles exhibitedductile fracture mode when measured at a temperature of 23° C.,according to ASTM D256-04.

In alternative embodiments using an x-ray contrast agent, an articlemolded from the thermoplastic composition and having a thickness of 3.2mm has a notched Izod impact (NII) strength of greater than or equal toabout 620 J/m, specifically greater than or equal to about 640 J/m, morespecifically greater than or equal to about 660 J/m, and still morespecifically greater than or equal to about 680 J/m, when measured at atemperature of 0° C., according to ASTM D256-04. Also in an embodiment,for a test set of at least 5 molded articles of 3.2 mm thickness andmolded from the thermoplastic composition, 100% of the articlesexhibited ductile fracture mode when measured at a temperature of 0° C.,according to ASTM D256-04.

In still other alternative embodiments using an x-ray contrast agent, anarticle molded from the thermoplastic composition and having a thicknessof 3.2 mm has a notched Izod impact (NII) strength of greater than orequal to about 475 J/m, specifically greater than or equal to about 480J/m, more specifically greater than or equal to about 490 J/m, and stillmore specifically greater than or equal to about 500 J/m, when measuredat a temperature of −10° C., according to ASTM D256-04. Also in anembodiment, for a test set of at least 5 molded articles of 3.2 mmthickness and molded from the thermoplastic composition, 100% of thearticles exhibited ductile fracture mode when measured at a temperatureof −10° C., according to ASTM D256-04.

In yet other alternative embodiments using an x-ray contrast agent, anarticle molded from the thermoplastic composition and having a thicknessof 3.2 mm has a notched Izod impact (NII) strength of greater than orequal to about 560 J/m, specifically greater than or equal to about 600J/m, more specifically greater than or equal to about 650 J/m, and stillmore specifically greater than or equal to about 674 J/m, when measuredat a temperature of −20° C., according to ASTM D256-04. Also in anembodiment, for a test set of at least 5 molded articles of 3.2 mmthickness and molded from the thermoplastic composition, 100% of thearticles exhibited ductile fracture mode when measured at a temperatureof −20° C., according to ASTM D256-04.

In still other alternative embodiments using an x-ray contrast agent, anarticle molded from the thermoplastic composition and having a thicknessof 3.2 mm has a notched Izod impact (NII) strength of greater than orequal to about 409 J/m, specifically greater than or equal to about 450J/m, more specifically greater than or equal to about 512 J/m, and stillmore specifically greater than or equal to about 527 J/m, when measuredat a temperature of −30° C., according to ASTM D256-04. Also in anembodiment, for a test set of at least 5 molded articles of 3.2 mmthickness and molded from the thermoplastic composition, 100% of thearticles exhibited ductile fracture mode when measured at a temperatureof −30° C., according to ASTM D256-04. It will be appreciated that thethermoplastic composition disclosed herein meets at least one of theforegoing notched Izod impact values measured at at least one of theforegoing temperatures of 23° C., 0° C., −10° C., −20° C., and/or −30°C.

In yet other alternative embodiments using an x-ray contrast agent, thesurface gloss of the thermoplastic composition, measured at an angle of60 degrees (°) on 3 mm colored chips, is greater than or equal to 90gloss units (GU), specifically greater than or equal to 95 GU, morespecifically greater than or equal to 96 GU, still more specificallygreater than or equal to 98 GU, and still more specifically greater thanor equal to 100 GU, according to ASTM D2457. The measure of glossaccording to this embodiment can be used a surrogate measurement forregularity and finish (i.e., smoothness) of the surface of the article,where increasing gloss correlates to an increase in surface smoothnessand therefore fewer surface defects for an article molded from thethermoplastic composition. In a specific embodiment, a high gloss ofgreater than 90 GU is desirable in a chocolate mold molded from thethermoplastic composition, wherein the high surface gloss and smoothnessof the chocolate mold proportionally imparts a desirable surface glossto chocolates molded in the chocolate mold.

In embodiments using a metal detectable agent, an article molded fromthe thermoplastic composition and having a thickness of 3.2 mm has anotched Izod impact (NII) strength of greater than or equal to 350 J/m,specifically greater than or equal to 400 J/m, more specifically greaterthan or equal to 450 J/m, and still more specifically greater than orequal to 500 J/m, when measured at a temperature of 23° C., according toASTM D256-04. Also in an embodiment, for a test set of at least 5 moldedarticles of 3.2 mm thickness and molded from the thermoplasticcomposition, 100% of the articles exhibited ductile fracture mode whenmeasured at a temperature of 23° C., according to ASTM D256-04.

In alternative embodiments using a metal detectable agent, an articlemolded from the thermoplastic composition and having a thickness of 3.2mm has a notched Izod impact (NII) strength of greater than or equal to200 J/m, specifically greater than or equal to 250 J/m, morespecifically greater than or equal to 300 J/m, and still morespecifically greater than or equal to 350 J/m, when measured at atemperature of 0° C., according to ASTM D256-04. Also in an embodiment,for a test set of at least 5 molded articles of 3.2 mm thickness andmolded from the thermoplastic composition, 100% of the articlesexhibited ductile fracture mode when measured at a temperature of 0° C.,according to ASTM D256-04.

In those embodiments wherein an x-ray contrast agent is used, an articlemolded from the thermoplastic composition demonstrates X-ray contrast.The article may be observed qualitatively by being observable in anX-ray image against a non-contrasting, or a less contrasting, backgroundmaterial. For example, an X-ray image of an article comprising thethermoplastic composition is observable against an article comprisingorganic material (such as a chocolate bar), a thermoplastic polymer(such as bisphenol A polycarbonate) or a composition identical to thethermoplastic composition of the instant invention but which does notinclude an X-ray contrast agent.

Alternatively, the X-ray contrast may be quantified by gray scalemeasurement of an X-ray image of an article comprising the thermoplasticcomposition. This can be accomplished by preparing a calibration curvethat correlates gray scale intensity with thickness for a series ofX-ray scattering standards (such as a series of aluminum films orplates, each having known thicknesses). X-ray transmission intensitythrough the standards may be quantified directly by irradiating thestandards (and samples) with X-ray radiation of a known intensity, andobtaining transmission data directly using an X-ray detector.Alternatively, a digital image of an irradiated standard may be obtainedusing a charge-coupled device, the gray shading of the resulting imagemay be pixelated, and the gray scale intensity of one or more sampleareas of the image may be averaged and thus used to determine overallgray-scale intensity for each standard (and sample). Plotting intensity(y-axis) versus thickness (x-axis) for each standard provides acorrelation by which intensity of a sample (molded from thethermoplastic composition, and of known thickness) can be translated toan equivalent thickness for the material of the standard. It has beenfound, using X-ray radiation of 50 to 80 kV and aluminum standards, thatan article of 3.2 mm thickness, molded from the thermoplasticcomposition has an Equivalent Aluminum (“Al”) thickness of greater than0.51 mm, compared with an equivalent Al thickness of 0.49 mm for acommercial grade bisphenol A polycarbonate.

Thus, in one embodiment, an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has an equivalent Althickness of greater than 0.51 mm, specifically greater than 0.52 mm,more specifically greater than 0.55 mm, and still more specificallygreater than or equal to 0.58 mm, when irradiated with 50 kV X-rayradiation.

In those embodiments wherein a metal detectable agent is used, anarticle molded from the thermoplastic composition demonstrates metaldetectability. For example, a metal detector will sound when an articleincluding the thermoplastic composition is scanned against an articleincluding an organic material (such as a chocolate bar), a thermoplasticpolymer (such as bisphenol A polycarbonate) or a composition identicalto the thermoplastic composition of the instant invention but which doesnot include the metal detectable agent.

Thus, thermoplastic compositions for molding or extruding applicationsrequiring X-ray contrast as well as minimal or no decomposition andretention of desirable mechanical properties are achieved by use of apolysiloxane-polycarbonate in combination with an X-ray contrast agentcomprising a small (less than 1 micrometer) median particle sizemagnetite, or a rutile titanate pigment. Alternatively, thermoplasticcompositions for molding or extruding applications requiring metaldetectability as well as minimal or no decomposition and retention ofdesirable mechanical properties are achieved by use of polycarbonate andpolysiloxane-polycarbonate in combination with a metal detectable agent.

The thermoplastic composition may be manufactured by methods generallyavailable in the art, for example, in one embodiment, in one manner ofproceeding, powdered polysiloxane-polycarbonate, the X-ray contrastagent or metal detectable agent, and any added polycarbonate, and otheradditives as desired are first mixed in a HENSCHEL MIXER® high speedmixer. Other low shear processes including but not limited to handmixing may also accomplish this blending. The blend is then fed into thethroat of an extruder via a hopper. Alternatively, one or more of thecomponents may be incorporated into the composition by feeding directlyinto the extruder at the throat and/or downstream through a sidestuffer.Additives may also be compounded into a masterbatch with a selectedpolymeric resin and fed into the extruder. In one embodiment, the x-raycontrast agent or metal detectable agent is previously compounded with apolysiloxane-polycarbonate masterbatch. The extruder is generallyoperated at a temperature higher than that necessary to cause thecomposition to flow, but at which temperature components of thethermoplastic composition do not decompose so as to significantlyadversely affect the composition. The extrudate is immediately quenchedin a water batch and pelletized. The pellets, so prepared, when cuttingthe extrudate may be one-fourth inch long or less as desired. Suchpellets may be used for subsequent molding, shaping, or forming.

In an x-ray contrast embodiment, a method of preparing a thermoplasticcomposition includes melt combining a polysiloxane-polycarbonate, X-raycontrast agent, and any added polycarbonate. The melt combining can bedone by extrusion. In one embodiment, the proportions ofpolysiloxane-polycarbonate, X-ray contrast agent, and any addedpolycarbonate are selected such that the resultant composition maximizesthe X-ray contrast capability while not significantly adverselyaffecting MVR (as determined by the MVR shift for samples measured atdwell times of 6 and 18 minutes as described hereinabove and asexemplified hereinbelow) or low temperature NII and ductility. In afurther specific embodiment, the thermoplastic polymer includes apolycarbonate-type polymer as defined hereinabove. In one embodiment, amethod of preparing a thermoplastic composition comprises melt blendinga masterbatch comprising polysiloxane-polycarbonate, X-ray contrastagent, and any added polycarbonate, with additionalpolysiloxane-polycarbonate and/or polycarbonate polymer.

In a metal detectable embodiment, a method of preparing a thermoplasticcomposition includes melt combining polycarbonate, apolysiloxane-polycarbonate copolymer and a metal detectable agent. Themelt combining can be done by extrusion. In an embodiment, theproportions of polycarbonate, polysiloxane-polycarbonate and metaldetectable agent are selected such that the resultant compositionmaximizes the metal detectable capability while not significantlyadversely low temperature NII and ductility.

In an x-ray contrast embodiment, including the X-ray contrast agentenhances the X-ray contrast of an article against a background material.In one embodiment, a method for increasing the X-ray contrast in anarticle including a polysiloxane-polycarbonate composition includescombining a contrast agent having a median particle size of less than orequal to 5 micrometers, with a polysiloxane-polycarbonate and optionallya polycarbonate, and forming the article from thepolysiloxane-polycarbonate composition. In one embodiment, the contrastagent includes an element having an atomic number of greater than orequal to 22.

In a specific embodiment, the extruder is a twin-screw extruder. Theextruder is typically operated at a temperature of 180 to 385° C.,specifically 200 to 330° C., more specifically 220 to 300° C., whereinthe die temperature may be different. The extruded thermoplasticcomposition is quenched in water and pelletized.

Shaped, formed, or molded articles including the thermoplasticcompositions are also provided. The thermoplastic compositions may bemolded into useful shaped articles by a variety of means such asinjection molding, extrusion, rotational molding, blow molding andthermoforming. In a specific embodiment, molding is done by injectionmolding. Beneficially, the thermoplastic composition has excellent moldfilling capability due to its high flow properties.

The thermoplastic composition can be provided as pellets, and is usefulto form articles, including articles for the food service industry suchas for example molds, utensils, trays, sheets, packaging, and the like;medical devices and consumables such as bottles, syringes, catheters,labware, and other articles and consumables; and toys including moldedplastic toys and packaging. In a specific embodiment, a useful articleis a mold for preparing candies, and in a more specific embodiment, themold is a mold for manufacturing chocolate.

In one embodiment, a mold for manufacturing chocolate and comprisingpolysiloxane-polycarbonate, optionally polycarbonate, and the X-raycontrast agent, exhibits X-ray contrast, wherein chocolates manufacturedwith the mold exhibit a high surface gloss and aesthetically pleasingappearance. In another embodiment, the chocolate mold includes 0.01 to10 parts by weight of an X-ray contrast agent including rutile titanatehaving a median particle size of less than or equal to about 5micrometers, magnetite having a median particle size of less than orequal to about 0.5 micrometers, or a combination including at least oneof the foregoing X-ray contrast agents. In an alternative embodiment, amold for manufacturing chocolate and includingpolysiloxane-polycarbonate, polycarbonate, and the metal detectableagent, exhibits metal detectability, wherein chocolates manufacturedwith the mold exhibit a high surface gloss and aesthetically pleasingappearance. In another embodiment, the chocolate mold includes 0.01 to10 parts by weight of a metal detectable agent.

While specific applications and articles are disclosed herein, oneskilled in the art will appreciate that the applications of thethermoplastic compositions herein should not be considered as limited tothese applications.

The thermoplastic composition is further illustrated by the followingnon-limiting examples.

All thermoplastic compositions for the examples (abbreviated Ex. in thefollowing tables) and comparative examples (abbreviated Cex. in thefollowing tables) were prepared using one or more of the followingcomponents listed in Table 1, to evaluate different inorganic compoundsfor use as metal detectable agents, and thereby determine the effect ofthese inorganic compounds on metal detectability of polycarbonate,polycarbonate-polysiloxane compositions.

All thermoplastic compositions were compounded on a Werner andPfleiderer ZSK 25-mm twin-screw extruder operating at temperatures offrom 260 to 300° C. The twin-screw extruder had enough distributive anddispersive mixing elements to produce good mixing of the polymercompositions. The compositions were subsequently dried at 120° C. for 4hours and then molded on a Husky or BOY injection-molding machine usingbarrel temperatures of from 270 to 300° C. and mold temperatures of from65 to 80° C. It will be recognized by one skilled in the art that theextrusion and molding methods are not limited to these temperatures.

The first set of examples and the data were for x-ray detectableembodiments of the present invention. The components used are set forthbelow in Table 1 and the corresponding results are set forth in Tables2-6 and FIGS. 1-4.

TABLE 1 Materials used for x-ray contrast embodiments ComponentDescription Source PC-Si LEXAN ™ EXL Polysiloxane-polycarbonate, 6 wtSABIC % dimethylsiloxane, average polysiloxane block Innovative lengthof 45 siloxane repeating units, Mw = Plastics 22,500-23,500 g/mol PC-1LEXAN ™ High Flow Bisphenol A (BPA) SABIC Polycarbonate MVR = 6-8 cc/10min at 300° C. Innovative under 1.2 kg load, Mw 21,600-21,900 g/molPlastics PC-2 LEXAN ™ BPA Polycarbonate, MVR = 10-12 cc/ SABIC 10 min at300° C. under 1.2 kg load, Mw = Innovative 29,500-29,900 g/mol PlasticsPC-3 LEXAN ™ BPA Polycarbonate (with mold release SABIC agent), MVR =10-12 cc/10 min at 300° C. under Innovative 1.2 kg load Plastics I-168IRGAFOS ® 168 antioxidant (Tris-(2,6-di-tert- Cibabutylphenyl)phosphite) Specialty Chemicals Barium Sulfate Powder, medianparticle size = 5-10 μm Polar Minerals Magnetite-1 MAGNIF ® 10functional filler with particle size Minelco, D₁₀ = 5 μm, D₅₀ = 10 μm(median particle size), The and D₉₀ = 25 μm Netherlands Bismuth OxidePowder, median particle size D₅₀ = 5-6 MCP Metal micrometers SpecialtiesBismuth Powder, median particle size D₅₀ = 7 μm MCP Metal SubcarbonateSpecialties Zinc Sulfide SACHTOLITH ® HD-S, median particle size D₅₀ =Sachtleben 0.3 μm Pigment Blue 28 Arctic Blue # 3 (Cobalt aluminateblue, spinel Shepherd pigment), median particle size D₅₀ = 1.4 μm ColorPigment Green 50 V11633 Cobalt titanate green, spinel pigment, Ferromedian particle size D₅₀ = 1.39 μm Pigment Yellow 53 SICOTAN ® Yellow K1010, Nickel Antimony BASF yellow, rutile titanate pigment, medianparticle size D₅₀ = 1.0 μm Pigment Brown 24 SICOTAN ® Yellow K 2001 FG,Chromium BASF Antimony yellow, rutile titanate pigment, median particlesize D₅₀ = 0.68 μm Pigment Yellow 163 METEOR ® Orange 7383, Chromiumtungsten BASF orange, rutile titanate pigment, median particle size D₅₀< 1.5 μm Magnetite SMT-01S Magnetite, median particle size D₅₀ = 0.3 μmSaehan Media Co., Ltd., Korea

Melt stability, measured as melt-volume rate (MVR) of the compositionswas determined by two techniques: MVR shift, which is a determination ofthe difference between MVR measured at a dwell time of 6 minutes, andthe MVR measured at a dwell time of 18 minutes; and the viscosity(rheological) change (referred to as “rheo change” in the followingtables), reported as the percentage change in final viscosity versus theinitial viscosity (i.e., where a negative value represents a decrease inviscosity, and a positive value represents an increase in viscosity) fora sample measured at 300° C. at a dwell time of 30 minutes. Therheological change is reported in units of percent and represents thechange in viscosity over the initial viscosity as a function of dwelltime. The rheology change method is based upon, but not in fullcompliance with, ISO 6721-10 and ASTM D4440. In the method, the testsample (in pellet form) is initially dried at 120° C. for 3 to 4 hours.The sample is then placed onto a parallel-plate or cone-plate rheometerfixture in a dynamic mechanical analyzer (DMA) and then heated to thedesired temperature (e.g., 300° C.). An inert gas (e.g., nitrogen) withcontrolled composition or purity was introduced as necessary to purgethe apparatus and thereby minimize possible thermal degradation of thetest sample.

MVR was determined at 300° C. under a load of 1.2 kg, and at dwell timesof 6 and 18 minutes and is reported in units of cc/10 min. according toASTM D1238-04. MVR shift (i.e., increase in MVR) is calculated accordingto the following equation:MVR Shift (%)={[(MVR@18 min)−(MVR@6 min)]/[MVR@6 min]}×100,where MVR @ 18 min. represents the MVR determined at a dwell time of 18minutes, and MVR @ 6 min. represents the MVR determined at a dwell timeof 6 minutes.

Notched Izod impact (NII) testing was determined on 3.2 mm thick barsaccording to ASTM D256-04, at temperatures of 23° C., 0° C., −10° C.,−20° C., and −30° C., where the NII impact strength is reported in unitsof joules per meter (J/m), and the percent ductility is defined as thepercent of molded sample articles in a test set of at least 5 sampleswhich exhibit ductile fracture mode. Surface gloss was tested accordingto ASTM D2457 at 60° using a Garden Gloss Meter and 3 mm thick colorchips and is reported in gloss units (GU) relative to a comparativegloss level of a standard black glass chip of 100 GU. The X-raymeasurements were made using a Torex D 150 X-ray tube with a 1.5 mm beamdiameter and an X-ray tube operating at 0-150 kV and 0-5 mA, purchasedfrom Northstar Imaging (Rogers, Minn.). The detector is a 9-inch (22.9cm) high-resolution image intensifier that can be used in this mode orin 6 inch (15 cm) or 4 inch (10 cm) modes allowing for a small amount ofmagnification. The instrument is also equipped with a 1-megapixeldigital camera allowing for real-time X-ray image analysis and digitalimage capture. The instrument settings were previously optimized toprovide good accuracy and precision. All measurements were taken usingthe 9-inch image intensifier, with the X-ray source operated at 50, 70or 80 kV, and 3 mA.

TABLE 2 Component CEx. 1 CEx. 2 CEx. 3 CEx. 4 CEx. 5 CEx. 6 CEx. 7 CEx.8 PC-1 (phr) 6 6 6 6 6 6 6 6 PC-2 (phr) 11 11 11 11 11 11 11 11 PC-Si(phr) 83 83 83 83 83 83 83 83 I-168 (phr) 0.06 0.06 0.06 0.06 0.06 0.060.06 0.06 Inorganic — Barium Barium Magnetite-1 Magnetite-1 BismuthBismuth Bismuth Compound Sulfate Sulfate Oxide Oxide SubcarbonateInorganic — 1 5 1 5 1 5 1 Compound Loading (phr) Total (phr) 100.06101.06 105.06 101.06 105.06 101.06 105.06 101.06 MVR (6 min. 10.5 10.311.0 10.4 10.5 11.2 27.3 64.1 dwell) cc/10 min MVR (18 min. 10.7 10.612.5 11.1 11.3 — — — dwell) cc/10 min MVR shift 2 3 14 7 8 — — — (6min/18 min) (%) Rheo −8 −11 −26 −11 −12 −10 −20 −18 Change (%) ComponentCEx. 9 CEx. 10 CEx. 11 CEx. 12 Ex. 1 Ex. 2 Ex. 3 PC-1 (phr) 6 6 6 6 6 66 PC-2 (phr) 11 11 11 11 11 11 11 PC-Si (phr) 83 83 83 83 83 83 83 I-168(phr) 0.06 0.06 0.06 0.06 0.06 0.06 0.06 Inorganic Bismuth Zinc PigmentPigment Pigment Pigment Pigment Compound Subcarbonate Sulfide Blue 28Green 50 Yellow Brown 24 Yellow 53 163 Inorganic 5 2 3 2 1 1 1 CompoundLoading (phr) Total (phr) 105.06 102.06 103.06 102.06 101.06 101.06101.06 MVR (6 min. 348 20 42 43 10.6 12 11.4 dwell) cc/10 min MVR (18min. — — — — 11.4 13.7 12.5 dwell) cc/10 min MVR shift — — — — 8 14 10(6 min/18 min) (%) Rheo −180 −8 −40 −28 −13 −20 −14 Change (%)

Table 2 shows the MVR data for the 14 compositions prepared as describedabove. Comparative Example 1 (CEx. 1) with no fillers or pigments had anMVR of 10.5 cc/10 min. under the conditions. Under an abusive dwell timeof 18 minutes, the MVR shift seen for CEx. 1 was minimal at 2%. Bariumsulfate and Magnetite-1 (CExs. 2-5) each showed good stability under theconditions studied as judged by the MVR data. However, 5% barium sulfate(CEx. 3) showed evidence of instability as seen in the 26% loss inviscosity in the dwell rheology test. The bismuth containing fillers(CEx. 6-9) cause the composition to degrade (e.g., a 3×-6× increase inMVR for CEx. 8 and 9 (bismuth subcarbonate)) even under standard 6minute dwell conditions, possibly due to the presence of ioniccontaminants (such as carbonates or metals) which can catalyzehydrolysis. Thus, bismuth fillers were eliminated as potentialcandidates for use. Passivating techniques (e.g., coating, acidquenching, or the like) may, however, potentially be used to treat suchfillers to eliminate melt stability issues upon compounding and thusincrease compatibility with polycarbonate.

Regarding the pigments, the zinc sulfide and the spinel-structuredpigments (Pigment Blue 28 and Pigment Green 50, CExs. 11 and 12,respectively) also degraded the polycarbonate composition (as seen in a2×-4× increase in MVR relative to CEx. 1) and are therefore not useful.The rutile titanate pigments (Exs. 1-3) as tested each showed good meltstability at both 6 and 18 minute dwells as compared to CEx. 1 withoutadded inorganic compound (i.e., MVR changes by less than 15% for each ofthese examples). Viscosity increase in the dwell rheology test was alsowithin acceptable limits for each of these examples (i.e., −20% to 0% orgreater).

Table 3 shows NII data for the compositions made with the inorganiccompounds.

TABLE 3 Component CEx. 1 CEx. 2 CEx. 3 CEx. 4 CEx. 5 CEx. 6 CEx. 7 CEx.8 Inorganic — Barium Barium Magnetite-1 Magnetite-1 Bismuth BismuthBismuth Compound Sulfate Sulfate Oxide Oxide Subcarbonate Inorganic — 15 1 5 1 5 1 Compound Loading (phr) NII (23° C.) Impact (J/m) 836 636 306463 194 723 427 505 Ductility (%) 100 100 100 100 100 100 60 100 NII (0°C.) Impact (J/m) — — — — — — — — Ductility (%) — — — — — — — — NII (−10°C.) Impact (J/m) 752 268 140 — — 472 175 349 Ductility (%) 100 80 0 — —100 0 60 NII (−20° C.) Impact (J/m) — — — — — — — — Ductility (%) — — —— — — — — NII (−30° C.) Impact (J/m) 733 — — 148 118 235 141 247Ductility (%) 100 — — 0 0 0 0 0 60° Gloss — — — 96.1 85.2 101.8 89.7 —Component CEx. 9 CEx. 10 CEx. 11 CEx. 12 Ex. 1 Ex. 2 Ex. 3 InorganicBismuth Zinc Pigment Pigment Pigment Pigment Pigment CompoundSubcarbonate Sulfide Blue 28 Green 50 Yellow Brown 24 Yellow 53 163Inorganic 5 2 3 2 1 1 1 Compound Loading (phr) NII (23° C.) Impact (J/m)108 688 495 532 810 784 793 Ductility (%) 0 100 100 100 100 100 100 NII(0° C.) Impact (J/m) — 618 390 342 741 733 740 Ductility (%) — 100 0 60100 100 100 NII (−10° C.) Impact (J/m) 104 — — — — — — Ductility (%) 0 —— — — — — NII (−20° C.) Impact (J/m) — 559 222 265 697 674 694 Ductility(%) — 100 0 0 100 100 100 NII (−30° C.) Impact (J/m) 86 512 208 207 650641 634 Ductility (%) 0 80 0 0 100 100 100 60° Gloss — — — — 100.3 100.995.7

As seen in the data in Table 3, thepolysiloxane-polycarbonate-containing compositions exhibited goodductile fracture mode properties at low temperatures. In Table 3, it canbe seen that CEx. 1 is ductile (i.e., 100% ductile fracture) at roomtemperature (23° C.) with an impact strength of 836 J/m as well asductility at −30° C. with an impact strength of 733 J/m. It is essentialthat the X-ray detectable formulation also retain this property.Addition of the inorganic compounds (pigments or fillers) thussignificantly reduces the impact strength, even at room temperature,depending on the filler loading as shown in the comparison of e.g., CEx.1 with CExs. 2 and 3; with CExs. 4 and 5; with CExs. 6 and 7; and with 8and 9, where each pair of comparative examples has a pigment or fillerloading of 1 and 5 phr.

Ductility is observed for all of the comparative Examples (CEx. 2-12) atroom temperature but the fracture mechanism changes to brittle mode,completely or partially depending on the identity of the filler, atlower temperatures. None of the filled comparative examples (CExs. 2-12)showed 100% ductility at −30° C. The median particle size of the fillersused ranged from 5-25 micrometers. The effect on impact properties forthese inorganic compounds is therefore significant due to composition ofthe inorganic compounds and particle size (see e.g. magnetite in CEx. 4and 5, and in Examples 4-8 below).

Table 3 shows the NII data for compositions containing zinc sulfide andvarious complex inorganic colored pigments, several of which containX-ray scattering metal ions (i.e., metals having an atomic number of 22or greater as defined hereinabove). Zinc sulfide and thespinel-structured pigment containing formulations (CExs. 10-12) eachshowed loss of impact strength and ductility relative tounfilled/unpigmented comparative example CEx. 1. The rutile titanatepigments (Exs. 1-3), however, each showed a minimal loss in impactstrength at room temperature (i.e., less than about 10%) and retainedductility. Surprisingly, even at −30° C., the same trend is also seen inthe compositions of Exs. 1-3, with these formulations showing less thana 10% drop in NII compared to CEx. 1, and 100% ductility at alltemperatures. For comparative purposes, the NII and ductility at −30° C.for PC-1, PC-2, and PC-3 are, respectively, 846 J/m (100% ductility),317 J/m (20% ductility), and 143 J/m (0% ductility) (not shown in Table3). Thus, rutile titanate pigments exhibit desirable NII and ductilityunlike the zinc sulfide or spinel pigments, and the rutile titanatepigments are therefore useful in preparing X-ray detectable compositionsthat retain their NII and ductility properties.

Table 3 also shows 60 degree gloss data determined for the compositionstested on color chips. The Pigment Yellow 163 formulation (Ex. 3) showsa slight loss of gloss (to about 95 GU, for a loss of about 5 relativeto the standard), however the loss is not as great as that observed forchips containing fillers (CEx. 5 containing magnetite at 5 phr with agloss of 85.2 GU, and CEx. 7 containing bismuth oxide at 5 phr with agloss of 89.7 GU). Retention of gloss is highly desirable for preparing,for example, molds for the chocolate industry, so that an aestheticallypleasing, glossy chocolate surface can be obtained for chocolatesprepared from the mold. Pigments (e.g., in Ex. 1-3) thus facilitate goodmold surface replication as opposed to fillers where surfaceimperfections may form due to larger particle size.

Decreasing particle size of the inorganic additives can lead to betterimpact retention and other properties, while still maintaining X-raycontrast. Magnetite with a median particle size of 0.2-0.5 micrometers(i.e., 200-500 nm; Magnetite SMT-01S in Table 1) was therefore evaluatedin the formulations shown in Table 4 below at five different loadings.

TABLE 4 Component Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 PC-1 (phr) 6 6 6 6 6PC-2 (phr) 11 11 11 11 11 PC-Si (phr) 83 83 83 83 83 I-168 (phr) 0.060.06 0.06 0.06 0.06 Magnetite (SMT-01S) 0.1 1 3 6 10 (phr) Total (phr)100.16 101.06 103.06 106.06 110.06 MVR (6 min. dwell) 9.85 9.74 9.9710.6 11.8 cc/10 min MVR (18 min. dwell) 9.67 9.65 11.9 11.6 17 cc/10 minMVR shift (6 min/ −2 −1 16 9 31 18 min) (%) Rheo Change (% change) −8−16 −16 −29 −39 NII (23° C.) Impact (J/m) 825 794 736 694 621 Ductility(%) 100 100 100 100 100 NII (−10° C.) Impact (J/m) 741 736 661 561 501Ductility (%) 100 100 100 100 100 NII (−30° C.) Impact (J/m) 697 643 605527 409 Ductility (%) 100 100 100 100 100 60° Gloss 100.9 100.9 100.9101.2 100.6

Table 4 shows the melt stability data as measured by MVR shift and dwellrheology measurements for the different compositions. Except for Ex. 8,which has the highest loading of magnetite nanoparticles (10 phr) andshows melt degradation (i.e., an MVR shift of 31%), all otherformulations are seen to be stable. Table 3 also shows the notched Izodimpact data at 23° C., −10° C. and −30° C. for the formulations tested.All the examples, from 0.1 to 10 phr loading of nanoparticulatemagnetite, show ductile fracture at all temperatures tested. The valueof the impact strength reduces as the loading of magnetite is increased(825 J/m for 0.1 phr loading in Ex. 4, compared to 621 J/m for 10 phrloading in Ex. 8, measured at 23° C.); however, the ductility (ductilefracture mode) is maintained. This observation holds true even at −30°C. Finally, 60 degree gloss of these formulations was measured and allthe values are high (>100 GU).

X-Ray Imaging. X-ray images to demonstrate enhanced contrast wereobtained for pellets of a rutile titanate formulation (Ex. 3). Since apotential application is in the manufacture of chocolate molds, thecontrast of pellets comprising the formulations against a bar ofchocolate was measured. Samples were analyzed at 70 kV (FIG. 1, A; FIG.2, A) using an Al filter to match the commercially used X-ray intensity,and at 50 kV (FIG. 1, B; FIG. 2, B) without a filter for added focus.FIG. 1 shows the contrast obtained with only a bar of chocolate in frontof the detector under the two conditions. FIG. 2 shows the contrastobtained with pellets of the Pigment Yellow 53 (i.e., nickel-antimonytitanate yellow pigment) composition of Ex. 3 sprinkled over thechocolate bar. The pellets are visible in FIG. 2; however, contrast canalso potentially be improved by making adjustments to the X-ray hardwareto refine beam focus and resolution, which is preferred to usingincreasing loading of titanates in the formulation.

FIG. 3 shows X-ray images of circular and rectangular molded plaques(3.2 mm thickness) of compounds of Exs. 4, 5, 7, and 8 (A, B, C, and Din FIG. 3, respectively) placed on a chocolate bar. Even at the lowestloading of 0.1 phr (Ex. 4; A in FIG. 3), the additive providessufficient contrast to be detected against a chocolate bar. This X-raycontrast imaging may be converted into gray-scale units and acalibration curve can be built which could allow for detection of e.g.,magnetite-containing contaminants, as discussed hereinbelow.

X-Ray Measurements. The X-ray contrast can also be quantified in termsof equivalent aluminum thickness, reported in units of thickness, i.e.,in millimeters (mm) of Al. In this method, a series of aluminum discs ofdifferent known thicknesses are measured and a correlation is obtainedbetween gray-scale or contrast and thickness of aluminum. The gray-scalefrom the sample of interest is then measured and the correlation is usedto determine the equivalent aluminum thickness.

For the calibration curve of the method, 1100 grade aluminum standardsat various known thicknesses were measured and an image of each standardwas acquired. A histogram of the pixel gray-scale within a 1″ (2.5 cm)sampling area and a histogram of a blank area (i.e., area with nosample) on the image were calculated. From each histogram, the mean andstandard deviation of the pixel values were calculated and the ratio ofthe blank pixel value to the standard pixel area was correlated to thealuminum thickness. A calibration curve was thus assembled using thenormalized pixel gray-scale value versus aluminum thickness. Analysis ofsamples was performed in the same manner as the calibration standardsand the equivalent aluminum thickness was determined by correlation ofthe obtained gray-scale value (y axis) to the corresponding equivalentaluminum thickness (x axis). A 1.57 mm aluminum sample was used as avalidation sample and the predictability was highly reproducible.

X-ray measurements were performed on 3.2 mm thick plaques using settingsof 50 kV and 3 mA. The grayscale data for each sample was converted intoequivalent aluminum thickness using a previously generated calibrationcurve correlating grayscale to thickness of aluminum discs as describedabove. The results are provided in Table 5.

TABLE 5 Inorganic Equivalent Al Compound thickness Inorganic CompoundLoading (phr) (mm Al) Control^(e) None — 0.49 CEx. 5 Magnetite-1 5 0.62CEx. 12 Pigment Green 50 2 0.46 Ex. 1 Pigment Yellow 53 1 0.48 Ex. 2Pigment Brown 24 1 0.52 Ex. 3 Pigment Yellow 163 1 0.48 Ex. 4 MagnetiteSMT-01S 0.1 0.56 Ex. 5 Magnetite SMT-01S 1 0.56 Ex. 6 Magnetite SMT-01S3 0.61 Ex. 7 Magnetite SMT-01S 6 0.73 Ex. 8 Magnetite SMT-01S 10 0.92^(e)PC-1

In Table 5, it can be seen that the lowest equivalent Al thickness of0.46 mm is obtained in CEx. 12, with a loading of 2 phr of aspinel-based pigment (Pigment Green 50). The greatest contrast (highestEquivalent Al thickness) generally is obtained using the magnetites,which exhibit an Equivalent Al thickness of 0.56 mm even at loadings aslow as 0.1 phr (Ex. 4, using magnetite particles of median particle size0.2-0.5 micrometers). The highest contrast is obtained for Ex. 8, whichincludes magnetite SMT-01S at a loading of 10 phr. It is also noted thatthe larger particle size magnetite (CEx. 5, 5-25 micrometer medianparticle size) has about the same Equivalent Al thickness of 0.62 mm asdoes the smaller median particle size magnetite (Ex. 6, 0.2-0.5micrometer median particle size) with an equivalent Al thickness of 0.61mm at a loading of 3 phr. For comparison purposes, polycarbonate withoutfiller or pigment has an equivalent Al thickness of 0.49 mm. It can beconcluded from this data that the smaller particle sizes allow for thesame X-ray contrast at a lower loading of the X-ray contrast agent thanwould be obtained for a larger particle size of the same X-ray contrastagent.

Release Measurements. Surface enrichment of the composition was alsocarried out. Table 6 shows the formulations studied for mold releaseproperties. CEx. 13 is the control batch, which does not contain anyadditive, Ex. 9 contains a pigment whereas CEx. 14 contains magnetitehaving a median particle size of 10 micrometers. In addition to thesebatches, a standard 10 cc/10 min. melt flow (300° C., 1.2 kg of downforce, 6 min. dwell) polycarbonate grade containing internal moldrelease (PC-3) was used as a control sample. PC-3 containspentaerythritol tetrastearate (PETS) as mold release agent in an amountof about 0.27 phr.

TABLE 6 Component Control CEx. 13^(a) Ex. 9^(b) CEx. 14^(c) PC-1 (phr) —6 6 6 PC-2 (phr) — 11 11 11 PC-3^(d) (phr) 100 — — — PC-Si (phr) — 83 8383 I-168 (phr) — 0.06 0.06 0.06 Pigment Yellow 53 (phr) — — 1 —Magnetite-1 (phr) — — — 5 Total (phr) 100 100.06 101.06 105.06^(a)Duplicate of CEx. 1 ^(b)Duplicate of Ex. 1 ^(c)Duplicate of CEx. 5^(d)Contains pentaerythritol tetrastearate (PETS) as mold release agentat 0.27 phr per 100 parts of polycarbonate in the PC-3 composition.

FIG. 4 shows the mold ejection pressure as a function of cycle time forCEx. 13, Ex. 9, and CEx. 14 and the control polycarbonate sample. Threedifferent cycle times, 80, 90 and 100 seconds, were studied. At eachcycle time, the polysiloxane-polycarbonate copolymers show almost halfthe ejection pressure of the polycarbonate sample, thus showing theadvantage of using these formulations. Ex. 9 and CEx. 14, which containthe X-ray detectable additive, also show consistently lower ejectionpressures than the non-additive containing CEx. 13. It is believed thatas a molded article cools (such as a chocolate mold immediately afterbeing formed), the siloxane chains orient themselves such that thesurface of an article molded from the polysiloxane-polycarbonatecomposition is enriched in siloxane. This phenomenon provides a numberof advantages of the polysiloxane-polycarbonate containing compositionover the polycarbonate composition without polysiloxane-polycarbonatepresent, chiefly (a) that it is easier release from the tool duringprocessing for the polysiloxane-polycarbonate containing article, and(b) there is reduced part-to-part friction for thepolysiloxane-polycarbonate containing article. Both these factors helpto improve surface replication and provide a smooth, glossy surface.Since polysiloxane-polycarbonate copolymers are used in chocolate moldsto retain the glossy appearance, it is necessary to ensure that theX-ray additive containing formulations will also show the same releaseproperties.

Thus the above Examples and Comparative Examples demonstrate that X-raydetectable additives can enhance the properties ofpolysiloxane-polycarbonate copolymer-containing compositions withoutcompromising properties such as mold release, melt flow, low temperatureductility, or gloss.

The second set of examples and the data were for metal detectableembodiments of the present invention. The components used are set forthbelow in Table 7 and the corresponding results are set forth in Tables 8and 9 and FIGS. 5 and 6.

TABLE 7 Materials used for metal detectable embodiments ComponentDescription Source PC-Si-2 LEXAN ™ EXL Polysiloxane-polycarbonate, 20 wtSABIC % dimethylsiloxane, average polysiloxane Innovative block lengthof 45 siloxane repeating units, Mw = Plastics 30,000 g/mol PC-Si-3LEXAN ™ EXL Polysiloxane-polycarbonate, 6 wt SABIC % dimethylsiloxane,average polysiloxane Innovative block length of 45 siloxane repeatingunits, Mw = Plastics 23,000 g/mol PC-4 LEXAN ™ Bisphenol A (BPA)Polycarbonate SABIC Mw 30,500 g/mol Innovative Plastics PC-5 LEXAN ™Bisphenol A (BPA) Polycarbonate SABIC Mw 26,200 g/mol InnovativePlastics PC-6 LEXAN ™ Bisphenol A (BPA) Polycarbonate SABIC Mw 21,800g/mol Innovative Plastics I-168 IRGAFOS ® 168 antioxidant(Tris-(2,6-di-tert- Ciba butylphenyl)phosphite) Specialty ChemicalsMagnetite-2 MAGNIF ® 10 functional filler with particle size Minelco,The D₁₀ = 6 μm, D₅₀ = 18 μm (median particle size), Netherlands and D₉₀= 41 μm SST Stainless steel fiber with polycarbonate resin and BekaertFibre sizing Technologies, Belgium Magnetite SMT-01S Magnetite, medianparticle size D₅₀ = 0.3 μm Saehan Media Co., Ltd., Korea

Notched Izod impact (NII) testing was determined on 3.2 mm thick barsaccording to ASTM D256-04, at temperatures of 23° C., 0° C., −10° C.,−20° C., and −30° C., where the NII impact strength is reported in unitsof joules per meter (J/m), and the percent ductility is defined as thepercent of molded sample articles in a test set of at least 5 sampleswhich exhibit ductile fracture mode.

Polycarbonate-polysiloxane formulations are known and used for theirductile fracture mode at low temperatures. All compositions were testedfor Notched Izod impact using standard ASTM D256 parameters fromtemperatures ranging from 23° C. to −30° C. From Table 8, we see thatthe control formulations show ductile fracture at room temperature withan impact strength of 748 J/m (Cex. 15), 725 J/m (Cex. 23) and 836 J/m.It is beneficial that the metal detectable formulation also be able toretain this property. Table 8 shows Notched Izod impact data for thecompositions made with metal detectable fillers. Addition of the fillerreduces impact strength significantly at room temperature by half oreven more for formulation based on solely polycarbonate (Cex. 16 to Cex.22) and formulations based on polycarbonate-polysiloxane-2 (Cex. 24 toCex. 30) with an overall siloxane level of 5 wt %.

Ductile impact is seen at room temperature only and in most cases,fracture mechanism changes to brittle mode, completely or partiallydepending on the filler at lower temperatures. Addition of the magnetite(fibers or powder) thus significantly reduced the impact strength, evenat room temperature, depending on the filler loading as shown in thecomparison.

For the polycarbonate formulations (Cex. 16 to Cex. 22) there is noformulation that shows ductile impact at 0° C. The average particle sizeof the fillers used ranged from 5-25 microns; hence effect on impactproperties is severe.

Surprisingly it is shown that the combinations of polysiloxane modifiedPC and Fe3O4 (Ex 11 to Ex 17) are less sensitive for ductilitydecreases. It is even more surprisingly the these formulations have anoverall siloxane level of 3.5%, lower then the overall siloxane level inCex. 24 to Cex. 30).

TABLE 8 Component Cex-15 Cex-16 Cex-17 Cex-18 Cex-19 Cex-20 Cex-21Cex-22 Cex-23 Cex-24 Cex-25 Cex-26 PC-4 wt % 30 30 30 30 30 30 30 30 1111 11 11 PC-5 wt % 70 70 70 70 70 70 70 70 PC-6 wt % 6 6 6 6 PC-Si-2 wt% PC-Si-3 wt % 83 83 83 83 I-168 wt % 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 0.06 0.06 0.06 0.06 SST wt % 0 1 2 0 1 2 Magnetite-2 wt % 1 2 4 6 81 Si content (%) 0 0 0 0 0 0 0 0 5 5 5 5 NII (23° C.) (J/m) 748 144 105160 118 105 97 82 725 462 314 389 NII retention (%) 100 19 14 21 16 1413 11 100 64 43 54 (23° C.) Ductility (%) 100 0 0 0 0 0 0 0 100 100 100100 NII (0° C.) (J/m) 557 115 98 121 126 100 94 88 690 382 260 247 NIIretention (%) 100 21 18 22 23 18 17 16 100 55 38 36 (0° C.) Ductility(%) 80 0 0 0 0 0 0 0 100 100 100 100 Component Cex-27 Cex-28 Cex-29Cex-30 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 PC-4 wt %11 11 11 11 62.5 62.5 62.5 62.5 62.5 62.5 62.5 62.5 PC-5 wt % 20 20 2020 20 20 20 20 PC-6 wt % 6 6 6 6 PC-Si-2 wt % 17.5 17.5 17.5 17.5 17.517.5 17.5 17.5 PC-Si-3 wt % 83 83 83 83 I-168 wt % 0.06 0.06 0.06 0.060.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 SST wt % 0 1 2 Magnetite-2 wt %2 4 6 8 1 2 4 6 8 Si content (%) 5 5 5 5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5NII (23° C.) (J/m) 233 152 130 119 836 605 520 634 512 313 221 193 NIIretention (%) 32 21 18 16 100 72 62 76 61 37 26 23 (23° C.) Ductility(%) 100 100 100 100 100 100 100 100 100 100 100 100 NII (0° C.) (J/m)148 119 110 102 769 507 381 449 291 185 148 146 NII retention (%) 21 1716 15 100 66 49 58 38 24 19 19 (0° C.) Ductility (%) 0 0 0 0 100 100 100100 100 80 0 0

As may be seen, decreasing the particle size of the inorganic additivescan lead to better impact retention and other properties, while stillmaintaining the metal detectablility was also within acceptable limitsfor each of these examples (i.e., −20% to 0% or greater).

TABLE 9 Component Cex-31 Cex-32 Cex-33 Cex-34 Ex. 18 Ex. 19 Ex. 20 Ex.21 PC-4 wt % 30 30 30 30 62.5 62.5 62.5 62.5 PC-5 wt % 70 70 70 70 20 2020 20 PC-6 wt % PC-Si-2 wt % 17.5 17.5 17.5 17.5 PC-Si-3 wt % I-168 wt %0.05 0.05 0.05 0.05 0.03 0.03 0.03 0.03 Magnetite SMT-01S wt % 0 1 2 4 01 2 4 Si content (%) 0 0 0 0 3.5 3.5 3.5 3.5 NII (23° C.) (J/m) 748 734742 611 836 819 811 824 NII (0° C.) (J/m) 557 598 477 170 769 771 778779 NII (−20° C.) (J/m) 174 164 252 147 788 741 743 719

As may be seen in Table 9, the Notched izod data for compositionscontaining Magnetite SMT-01S is provided and it can be seen that theparticle size of the magnetite may be adjusted to achieve selectedcharacteristics. In these examples, smaller particle size magnetite wasused. In those samples having both the polycarbonate and thepolycarbonate-polysiloxane copolymer, the resulting impact strength wasmuch greater than those samples having no polycarbonate-polysiloxanecopolymer and these materials also had higher impact strengths thanthose corresponding samples using larger particle size magnetite (Ex.13-15). So while larger particle size magnetite helped retain a greaterimpact strength than stainless steel fiber, if higher impact strength isa selected characteristic, then these examples would indicate thatsmaller particle size magnetite will help retain a higher percentage ofNII than larger particle size magnetite.

FIGS. 5 and 6 also help show that polysiloxane based polycarbonate andFe3O4 show good toughness, and toughness retention at low temperature.The data shown relates to 0, 3.5 and 5 total wt. % Si. In line withthese results, as expected and shown in FIG. 7 and Table 10, fatigue(which is a beneficial property for chocolate molds) for PC Si-basedsystem was significantly better compared to PC-based system (0% totalwt. % Si) in the presence of magnetite.

TABLE 10 No of cycles Sample Stress, to no. Mpa failure aver std PC-4 130 19171 22703.5 4995.709 2 30 26236 PC-4 + 1% Magnetite- 1 30 1879517308.5 2102.228 2 2 30 15822 PC-4 + 2% Magnetite- 1 30 16112 15127 13932 2 30 14142 PC-4 + 4% Magnetite- 1 30 13308 14483 1661.701 2 2 30 15658PC-Si-2 1 30 85544 84379.5 1646.852 2 30 83215 PC-Si-2 + 1% 1 30 4344542738 999.849 Magnetite-2 2 30 42031 PC-Si-2 + 2% 1 30 44891 441081107.329 Magnetite-2 2 30 43325 PC-Si-2 + 4% 1 30 46537 43638 4099.805Magnetite-2 2 30 40739 PC-Si-2 + 6% 1 30 41818 42436.5 874.6911Magnetite-2 2 30 43055

Thus the above Examples and Comparative Examples demonstrate that metaldetectable additives can also enhance the properties ofpolysiloxane-polycarbonate copolymer-containing compositions withoutcompromising properties such as mold release, melt flow, low temperatureductility, or gloss.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, it should further be noted that the terms “first,”“second,” and the like herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (e.g., itincludes the degree of error associated with measurement of theparticular quantity).

We claim:
 1. A thermoplastic composition comprising: from 65 to 95% byweight of polycarbonate; from 5 to 35% by weight of apolysiloxane-polycarbonate copolymer; and from 0.01 to 10% by weight ofa metal detectable agent having a median particle size of less than orequal to 5 micrometers; wherein the thermoplastic composition has asiloxane content of 0.1 to 4 wt % siloxane units, based on the totalweight of the thermoplastic composition, wherein an article molded fromthe thermoplastic composition and having a thickness of 3.2 mm has anotched Izod impact (NII) strength of greater than or equal to 500 J/m,when measured at a temperature of 23° C. according to ASTM D256-04, anda notched Izod impact strength of greater than or equal to 350 J/m, whenmeasured at a temperature of 0° C. according to ASTM D256-04.
 2. Thecomposition of claim 1, wherein the polysiloxane-polycarbonate copolymercomprises 65 to 85 wt % of carbonate units and 5-35 wt % siloxane units,based on the total weight of the polysiloxane-polycarbonate.
 3. Thecomposition of claim 1, comprising polysiloxane-polycarbonate in anamount of 10 to 25 parts by weight, and polycarbonate in an amount of 75to 90 parts by weight, based on combined 100 parts by weight ofpolysiloxane-polycarbonate and any added polycarbonate.
 4. Thecomposition of claim 1, wherein the metal detectable agent has a medianparticle size of 0.01 to 0.5 micrometers.
 5. The composition of claim 1,wherein the metal detectable agent has a median particle size of lessthan or equal to 1 micrometer.
 6. The composition of claim 1, whereinthe metal detectable agent is a ferrous metal.
 7. The composition ofclaim 6, wherein the metal detectable agent comprises magnetite.
 8. Thecomposition of claim 7, wherein the magnetite has a median particle sizeof 0.01 to about 0.5 micrometers.
 9. The composition of claim 1 whereinthe polysiloxane-polycarbonate copolymer comprises 65 to 85 wt % ofcarbonate units and 5-35 wt % siloxane units, based on the total weightof the polysiloxane-polycarbonate.
 10. The composition of claim 1,wherein the thermoplastic composition further comprises additivesincluding impact modifiers, fillers, colorants including dyes andpigments, antioxidants, heat stabilizers, light, stabilizers, UV lightstabilizers, plasticizers, lubricants, mold release agents, flameretardants, antistatic agents, anti-drip agents, radiation stabilizers,or a combination comprising at least one of the foregoing additives. 11.An article comprising a thermoplastic composition comprising: from 65 to95% by weight of polycarbonate; from 5 to 35% by weight of apolysiloxane-polycarbonate copolymer; and from 0.01 to 10% by weight ofmagnetite having a median particle size of less than or equal to 5micrometers; wherein the thermoplastic composition has a siloxanecontent of 0.1 to 4 wt % siloxane units, based on the total weight ofthe thermoplastic composition, wherein an article molded from thethermoplastic composition and having a thickness of 3.2 mm has a notchedIzod impact (NII) strength of greater than or equal to 500 J/m, whenmeasured at a temperature of 23° C. according to ASTM D256-04, and anotched Izod impact strength of greater than or equal to 350 J/m, whenmeasured at a temperature of 0° C. according to ASTM D256-04.
 12. Thearticle of claim 11, wherein the article is an article for the foodservice industry, a medical device, or a toy.
 13. A mold formanufacturing a food product, comprising a thermoplastic compositioncomprising: a) from 65 to 95% by weight of polycarbonate; b) from 5 to35% by weight of a polysiloxane-polycarbonate copolymer; and c) from0.01 to 10% by weight of a metal detectable agent having a medianparticle size of less than or equal to 5 micrometers; wherein thethermoplastic composition has a siloxane content of 0.1 to 4 wt %siloxane units, based on the total weight of the thermoplasticcomposition, wherein an article molded from the thermoplasticcomposition and having a thickness of 3.2 mm has a notched Izod impact(NII) strength of greater than or equal to 500 J/m, when measured at atemperature of 23° C. according to ASTM D256-04, and a notched Izodimpact strength of greater than or equal to 350 J/m, when measured at atemperature of 0° C. according to ASTM D256-04; wherein degradation ofthe mold is metal detectable.
 14. A method for increasing the metaldetectability in an article comprising a thermoplastic composition,comprising combining a metal detectable agent having a median particlesize of less than or equal to 5 micrometers with polycarbonate and apolysiloxane-polycarbonate copolymer to form the thermoplasticcomposition; wherein the thermoplastic composition has a siloxanecontent of 0.1 to 4 wt % siloxane units, based on the total weight ofthe thermoplastic composition; and forming the article from thethermoplastic composition, wherein a molded article, molded from thethermoplastic composition and having a thickness of 3.2 mm has a notchedIzod impact (NII) strength of greater than or equal to 500 J/m, whenmeasured at a temperature of 23° C. according to ASTM D256-04, and anotched Izod impact strength of greater than or equal to 350 J/m, whenmeasured at a temperature of 0° C. according to ASTM D256-04.